diff --git a/promql/generated_parser.y b/promql/generated_parser.y
index 73c4531b62..dc7d3698d4 100644
--- a/promql/generated_parser.y
+++ b/promql/generated_parser.y
@@ -199,7 +199,7 @@ aggregate_expr  : aggregate_op aggregate_modifier function_call_body
                 | aggregate_op function_call_body
                         { $$ = yylex.(*parser).newAggregateExpr($1, &AggregateExpr{}, $2) }
                 | aggregate_op error
-                        { yylex.(*parser).unexpected("aggregation","") }
+                        { yylex.(*parser).unexpected("aggregation",""); $$ = nil }
                 ;
 
 aggregate_modifier:
@@ -294,7 +294,7 @@ grouping_labels : LEFT_PAREN grouping_label_list RIGHT_PAREN
                 | LEFT_PAREN RIGHT_PAREN
                         { $$ = []string{} }
                 | error
-                        { yylex.(*parser).unexpected("grouping opts", "\"(\"") }
+                        { yylex.(*parser).unexpected("grouping opts", "\"(\""); $$ = nil }
                 ;
 
 
@@ -304,7 +304,7 @@ grouping_label_list:
                 | grouping_label
                         { $$ = []string{$1.Val} }
                 | grouping_label_list error
-                        { yylex.(*parser).unexpected("grouping opts", "\",\" or \")\"") }
+                        { yylex.(*parser).unexpected("grouping opts", "\",\" or \")\""); $$ = $1 }
                 ;
 
 grouping_label  : maybe_label
@@ -315,7 +315,7 @@ grouping_label  : maybe_label
                         $$ = $1
                         }
                 | error
-                        { yylex.(*parser).unexpected("grouping opts", "label") }
+                        { yylex.(*parser).unexpected("grouping opts", "label"); $$ = Item{} }
                 ;
 
 /*
@@ -349,6 +349,11 @@ function_call_args: function_call_args COMMA expr
                         { $$ = append($1.(Expressions), $3.(Expr)) }
                 | expr 
                         { $$ = Expressions{$1.(Expr)} }
+                | function_call_args COMMA
+                        {
+                        yylex.(*parser).failf($2.PositionRange(), "trailing commas not allowed in function call args")
+                        $$ = $1
+                        }
                 ;
 
 /*
@@ -369,7 +374,7 @@ offset_expr: expr OFFSET duration
                         $$ = $1
                         }
                 | expr OFFSET error
-                        { yylex.(*parser).unexpected("offset", "duration") }
+                        { yylex.(*parser).unexpected("offset", "duration"); $$ = $1 }
                 ;
 
 /*
@@ -410,13 +415,13 @@ subquery_expr   : expr LEFT_BRACKET duration COLON maybe_duration RIGHT_BRACKET
                         }
                         }
                 | expr LEFT_BRACKET duration COLON duration error
-                        { yylex.(*parser).unexpected("subquery selector", "\"]\"") }
+                        { yylex.(*parser).unexpected("subquery selector", "\"]\""); $$ = $1 }
                 | expr LEFT_BRACKET duration COLON error
-                        { yylex.(*parser).unexpected("subquery selector", "duration or \"]\"") }
+                        { yylex.(*parser).unexpected("subquery selector", "duration or \"]\""); $$ = $1 }
                 | expr LEFT_BRACKET duration error
-                        { yylex.(*parser).unexpected("subquery or range", "\":\" or \"]\"") }
+                        { yylex.(*parser).unexpected("subquery or range", "\":\" or \"]\""); $$ = $1 }
                 | expr LEFT_BRACKET error
-                        { yylex.(*parser).unexpected("subquery selector", "duration") }
+                        { yylex.(*parser).unexpected("subquery selector", "duration"); $$ = $1 }
                 ;
 
 /*
@@ -493,21 +498,27 @@ label_matchers  : LEFT_BRACE label_match_list RIGHT_BRACE
                 ;
 
 label_match_list: label_match_list COMMA label_matcher
-                        { $$ = append($1, $3)}
+                        { 
+                        if $1 != nil{
+                                $$ = append($1, $3)
+                        } else {
+                                $$ = $1
+                        }
+                        }
                 | label_matcher
                         { $$ = []*labels.Matcher{$1}}
                 | label_match_list error
-                        { yylex.(*parser).unexpected("label matching", "\",\" or \"}\"") }
+                        { yylex.(*parser).unexpected("label matching", "\",\" or \"}\""); $$ = $1 }
                 ;
 
 label_matcher   : IDENTIFIER match_op STRING
-                        { $$ = yylex.(*parser).newLabelMatcher($1, $2, $3) }
+                        { $$ = yylex.(*parser).newLabelMatcher($1, $2, $3);  }
                 | IDENTIFIER match_op error
-                        { yylex.(*parser).unexpected("label matching", "string")}
+                        { yylex.(*parser).unexpected("label matching", "string"); $$ = nil}
                 | IDENTIFIER error 
-                        { yylex.(*parser).unexpected("label matching", "label matching operator") } 
+                        { yylex.(*parser).unexpected("label matching", "label matching operator"); $$ = nil } 
                 | error
-                        { yylex.(*parser).unexpected("label matching", "identifier or \"}\"")}
+                        { yylex.(*parser).unexpected("label matching", "identifier or \"}\""); $$ = nil}
                 ;
                         
 /*
@@ -538,18 +549,18 @@ label_set_list  : label_set_list COMMA label_set_item
                 | label_set_item
                         { $$ = []labels.Label{$1} }
                 | label_set_list error
-                        { yylex.(*parser).unexpected("label set", "\",\" or \"}\"", ) }
+                        { yylex.(*parser).unexpected("label set", "\",\" or \"}\"", ); $$ = $1 }
                 
                 ;
 
 label_set_item  : IDENTIFIER EQL STRING
                         { $$ = labels.Label{Name: $1.Val, Value: yylex.(*parser).unquoteString($3.Val) } } 
                 | IDENTIFIER EQL error
-                        { yylex.(*parser).unexpected("label set", "string")}
+                        { yylex.(*parser).unexpected("label set", "string"); $$ = labels.Label{}}
                 | IDENTIFIER error
-                        { yylex.(*parser).unexpected("label set", "\"=\"")}
+                        { yylex.(*parser).unexpected("label set", "\"=\""); $$ = labels.Label{}}
                 | error
-                        { yylex.(*parser).unexpected("label set", "identifier or \"}\"") }
+                        { yylex.(*parser).unexpected("label set", "identifier or \"}\""); $$ = labels.Label{} }
                 ;
 
 /*
@@ -572,7 +583,7 @@ series_values   : /*empty*/
                 | series_values SPACE
                         { $$ = $1 }
                 | error
-                        { yylex.(*parser).unexpected("series values", "") }
+                        { yylex.(*parser).unexpected("series values", ""); $$ = nil }
                 ;
 
 series_item     : BLANK
diff --git a/promql/generated_parser.y.go b/promql/generated_parser.y.go
index 99d568b659..2f7608da7e 100644
--- a/promql/generated_parser.y.go
+++ b/promql/generated_parser.y.go
@@ -183,7 +183,7 @@ const yyEofCode = 1
 const yyErrCode = 2
 const yyInitialStackSize = 16
 
-//line promql/generated_parser.y:695
+//line promql/generated_parser.y:706
 
 //line yacctab:1
 var yyExca = [...]int{
@@ -191,55 +191,55 @@ var yyExca = [...]int{
 	1, -1,
 	-2, 0,
 	-1, 15,
-	1, 102,
-	10, 102,
-	22, 102,
+	1, 103,
+	10, 103,
+	22, 103,
 	-2, 0,
 	-1, 157,
-	12, 163,
-	13, 163,
-	16, 163,
-	17, 163,
-	23, 163,
-	26, 163,
-	42, 163,
-	45, 163,
-	46, 163,
-	47, 163,
-	48, 163,
-	49, 163,
-	50, 163,
-	51, 163,
-	52, 163,
-	53, 163,
-	54, 163,
-	55, 163,
+	12, 164,
+	13, 164,
+	16, 164,
+	17, 164,
+	23, 164,
+	26, 164,
+	42, 164,
+	45, 164,
+	46, 164,
+	47, 164,
+	48, 164,
+	49, 164,
+	50, 164,
+	51, 164,
+	52, 164,
+	53, 164,
+	54, 164,
+	55, 164,
 	-2, 0,
 	-1, 158,
-	12, 163,
-	13, 163,
-	16, 163,
-	17, 163,
-	23, 163,
-	26, 163,
-	42, 163,
-	45, 163,
-	46, 163,
-	47, 163,
-	48, 163,
-	49, 163,
-	50, 163,
-	51, 163,
-	52, 163,
-	53, 163,
-	54, 163,
-	55, 163,
+	12, 164,
+	13, 164,
+	16, 164,
+	17, 164,
+	23, 164,
+	26, 164,
+	42, 164,
+	45, 164,
+	46, 164,
+	47, 164,
+	48, 164,
+	49, 164,
+	50, 164,
+	51, 164,
+	52, 164,
+	53, 164,
+	54, 164,
+	55, 164,
 	-2, 0,
 	-1, 174,
-	19, 161,
+	19, 162,
 	-2, 0,
 	-1, 221,
-	19, 162,
+	19, 163,
 	-2, 0,
 }
 
@@ -342,17 +342,17 @@ var yyR1 = [...]int{
 	25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
 	24, 26, 26, 36, 36, 31, 31, 31, 31, 14,
 	14, 14, 14, 13, 13, 13, 4, 4, 28, 30,
-	30, 29, 29, 37, 35, 35, 33, 39, 39, 39,
-	39, 39, 40, 41, 41, 41, 32, 32, 32, 1,
-	1, 1, 2, 2, 2, 2, 11, 11, 7, 7,
-	9, 9, 9, 9, 10, 10, 10, 12, 12, 12,
-	12, 45, 17, 17, 17, 17, 16, 16, 16, 16,
-	16, 20, 20, 20, 3, 3, 3, 3, 3, 3,
-	3, 3, 3, 3, 3, 6, 6, 6, 6, 6,
+	30, 29, 29, 29, 37, 35, 35, 33, 39, 39,
+	39, 39, 39, 40, 41, 41, 41, 32, 32, 32,
+	1, 1, 1, 2, 2, 2, 2, 11, 11, 7,
+	7, 9, 9, 9, 9, 10, 10, 10, 12, 12,
+	12, 12, 45, 17, 17, 17, 17, 16, 16, 16,
+	16, 16, 20, 20, 20, 3, 3, 3, 3, 3,
+	3, 3, 3, 3, 3, 3, 6, 6, 6, 6,
 	6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 8, 8,
-	5, 5, 5, 5, 34, 19, 21, 21, 18, 42,
-	38, 43, 43, 15, 15,
+	6, 6, 6, 6, 6, 6, 6, 6, 6, 8,
+	8, 5, 5, 5, 5, 34, 19, 21, 21, 18,
+	42, 38, 43, 43, 15, 15,
 }
 var yyR2 = [...]int{
 
@@ -362,17 +362,17 @@ var yyR2 = [...]int{
 	4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
 	1, 0, 1, 3, 3, 1, 1, 3, 3, 3,
 	4, 2, 1, 3, 1, 2, 1, 1, 2, 3,
-	2, 3, 1, 3, 3, 3, 4, 6, 6, 5,
-	4, 3, 2, 2, 1, 1, 3, 4, 2, 3,
-	1, 2, 3, 3, 2, 1, 2, 1, 1, 1,
-	3, 4, 2, 0, 3, 1, 2, 3, 3, 2,
-	1, 2, 0, 3, 2, 1, 1, 3, 1, 3,
-	4, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+	2, 3, 1, 2, 3, 3, 3, 4, 6, 6,
+	5, 4, 3, 2, 2, 1, 1, 3, 4, 2,
+	3, 1, 2, 3, 3, 2, 1, 2, 1, 1,
+	1, 3, 4, 2, 0, 3, 1, 2, 3, 3,
+	2, 1, 2, 0, 3, 2, 1, 1, 3, 1,
+	3, 4, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 2, 2, 1, 1,
-	1, 0, 1, 0, 1,
+	1, 1, 1, 1, 1, 1, 1, 2, 2, 1,
+	1, 1, 0, 1, 0, 1,
 }
 var yyChk = [...]int{
 
@@ -403,30 +403,30 @@ var yyChk = [...]int{
 }
 var yyDef = [...]int{
 
-	0, -2, 93, 93, 0, 0, 7, 6, 1, 93,
-	87, 88, 89, 0, 2, -2, 3, 4, 8, 9,
+	0, -2, 94, 94, 0, 0, 7, 6, 1, 94,
+	88, 89, 90, 0, 2, -2, 3, 4, 8, 9,
 	10, 11, 12, 13, 14, 15, 16, 17, 18, 0,
-	89, 154, 0, 160, 0, 74, 75, 114, 115, 116,
-	117, 118, 119, 120, 121, 122, 123, 124, 148, 149,
-	0, 5, 86, 0, 92, 95, 0, 100, 101, 105,
+	90, 155, 0, 161, 0, 75, 76, 115, 116, 117,
+	118, 119, 120, 121, 122, 123, 124, 125, 149, 150,
+	0, 5, 87, 0, 93, 96, 0, 101, 102, 106,
 	41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
 	41, 41, 41, 41, 41, 0, 0, 0, 21, 22,
-	0, 0, 0, 58, 0, 72, 73, 0, 78, 80,
-	0, 85, 90, 0, 96, 0, 99, 104, 0, 40,
+	0, 0, 0, 58, 0, 73, 74, 0, 79, 81,
+	0, 86, 91, 0, 97, 0, 100, 105, 0, 40,
 	45, 46, 42, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 64, 65, 159,
-	0, 71, 19, 20, 23, 0, 52, 24, 0, 60,
-	62, 63, 76, 0, 81, 0, 84, 150, 151, 152,
-	153, 91, 94, 97, 98, 103, 106, 108, 111, 112,
-	113, 155, 0, 0, 25, 0, 0, -2, -2, 26,
+	0, 0, 0, 0, 0, 0, 0, 65, 66, 160,
+	0, 72, 19, 20, 23, 0, 52, 24, 0, 60,
+	62, 64, 77, 0, 82, 0, 85, 151, 152, 153,
+	154, 92, 95, 98, 99, 104, 107, 109, 112, 113,
+	114, 156, 0, 0, 25, 0, 0, -2, -2, 26,
 	27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
-	37, 38, 39, 66, -2, 70, 0, 51, 54, 56,
-	57, 125, 126, 127, 128, 129, 130, 131, 132, 133,
-	134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
-	144, 145, 146, 147, 59, 0, 77, 79, 82, 83,
-	0, 0, 0, 156, 157, 43, 44, 47, 164, 48,
-	0, -2, 69, 49, 0, 55, 61, 107, 158, 109,
-	0, 67, 68, 50, 53, 110,
+	37, 38, 39, 67, -2, 71, 0, 51, 54, 56,
+	57, 126, 127, 128, 129, 130, 131, 132, 133, 134,
+	135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
+	145, 146, 147, 148, 59, 63, 78, 80, 83, 84,
+	0, 0, 0, 157, 158, 43, 44, 47, 165, 48,
+	0, -2, 70, 49, 0, 55, 61, 108, 159, 110,
+	0, 68, 69, 50, 53, 111,
 }
 var yyTok1 = [...]int{
 
@@ -837,6 +837,7 @@ yydefault:
 //line promql/generated_parser.y:202
 		{
 			yylex.(*parser).unexpected("aggregation", "")
+			yyVAL.node = nil
 		}
 	case 23:
 		yyDollar = yyS[yypt-2 : yypt+1]
@@ -1016,6 +1017,7 @@ yydefault:
 //line promql/generated_parser.y:297
 		{
 			yylex.(*parser).unexpected("grouping opts", "\"(\"")
+			yyVAL.strings = nil
 		}
 	case 53:
 		yyDollar = yyS[yypt-3 : yypt+1]
@@ -1034,6 +1036,7 @@ yydefault:
 //line promql/generated_parser.y:307
 		{
 			yylex.(*parser).unexpected("grouping opts", "\",\" or \")\"")
+			yyVAL.strings = yyDollar[1].strings
 		}
 	case 56:
 		yyDollar = yyS[yypt-1 : yypt+1]
@@ -1049,6 +1052,7 @@ yydefault:
 //line promql/generated_parser.y:318
 		{
 			yylex.(*parser).unexpected("grouping opts", "label")
+			yyVAL.item = Item{}
 		}
 	case 58:
 		yyDollar = yyS[yypt-2 : yypt+1]
@@ -1092,27 +1096,35 @@ yydefault:
 			yyVAL.node = Expressions{yyDollar[1].node.(Expr)}
 		}
 	case 63:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:359
+		yyDollar = yyS[yypt-2 : yypt+1]
+//line promql/generated_parser.y:353
 		{
-			yyVAL.node = &ParenExpr{Expr: yyDollar[2].node.(Expr), PosRange: mergeRanges(&yyDollar[1].item, &yyDollar[3].item)}
+			yylex.(*parser).failf(yyDollar[2].item.PositionRange(), "trailing commas not allowed in function call args")
+			yyVAL.node = yyDollar[1].node
 		}
 	case 64:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:367
+//line promql/generated_parser.y:364
 		{
-			yylex.(*parser).addOffset(yyDollar[1].node, yyDollar[3].duration)
-			yyVAL.node = yyDollar[1].node
+			yyVAL.node = &ParenExpr{Expr: yyDollar[2].node.(Expr), PosRange: mergeRanges(&yyDollar[1].item, &yyDollar[3].item)}
 		}
 	case 65:
 		yyDollar = yyS[yypt-3 : yypt+1]
 //line promql/generated_parser.y:372
 		{
-			yylex.(*parser).unexpected("offset", "duration")
+			yylex.(*parser).addOffset(yyDollar[1].node, yyDollar[3].duration)
+			yyVAL.node = yyDollar[1].node
 		}
 	case 66:
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:377
+		{
+			yylex.(*parser).unexpected("offset", "duration")
+			yyVAL.node = yyDollar[1].node
+		}
+	case 67:
 		yyDollar = yyS[yypt-4 : yypt+1]
-//line promql/generated_parser.y:380
+//line promql/generated_parser.y:385
 		{
 			var errMsg string
 			vs, ok := yyDollar[1].node.(*VectorSelector)
@@ -1133,9 +1145,9 @@ yydefault:
 				EndPos:         yylex.(*parser).lastClosing,
 			}
 		}
-	case 67:
+	case 68:
 		yyDollar = yyS[yypt-6 : yypt+1]
-//line promql/generated_parser.y:403
+//line promql/generated_parser.y:408
 		{
 			yyVAL.node = &SubqueryExpr{
 				Expr:  yyDollar[1].node.(Expr),
@@ -1145,33 +1157,37 @@ yydefault:
 				EndPos: yyDollar[6].item.Pos + 1,
 			}
 		}
-	case 68:
+	case 69:
 		yyDollar = yyS[yypt-6 : yypt+1]
-//line promql/generated_parser.y:413
+//line promql/generated_parser.y:418
 		{
 			yylex.(*parser).unexpected("subquery selector", "\"]\"")
-		}
-	case 69:
-		yyDollar = yyS[yypt-5 : yypt+1]
-//line promql/generated_parser.y:415
-		{
-			yylex.(*parser).unexpected("subquery selector", "duration or \"]\"")
+			yyVAL.node = yyDollar[1].node
 		}
 	case 70:
-		yyDollar = yyS[yypt-4 : yypt+1]
-//line promql/generated_parser.y:417
+		yyDollar = yyS[yypt-5 : yypt+1]
+//line promql/generated_parser.y:420
 		{
-			yylex.(*parser).unexpected("subquery or range", "\":\" or \"]\"")
+			yylex.(*parser).unexpected("subquery selector", "duration or \"]\"")
+			yyVAL.node = yyDollar[1].node
 		}
 	case 71:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:419
+		yyDollar = yyS[yypt-4 : yypt+1]
+//line promql/generated_parser.y:422
 		{
-			yylex.(*parser).unexpected("subquery selector", "duration")
+			yylex.(*parser).unexpected("subquery or range", "\":\" or \"]\"")
+			yyVAL.node = yyDollar[1].node
 		}
 	case 72:
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:424
+		{
+			yylex.(*parser).unexpected("subquery selector", "duration")
+			yyVAL.node = yyDollar[1].node
+		}
+	case 73:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:429
+//line promql/generated_parser.y:434
 		{
 			if nl, ok := yyDollar[2].node.(*NumberLiteral); ok {
 				if yyDollar[1].item.Typ == SUB {
@@ -1183,9 +1199,9 @@ yydefault:
 				yyVAL.node = &UnaryExpr{Op: yyDollar[1].item.Typ, Expr: yyDollar[2].node.(Expr), StartPos: yyDollar[1].item.Pos}
 			}
 		}
-	case 73:
+	case 74:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:447
+//line promql/generated_parser.y:452
 		{
 			vs := yyDollar[2].node.(*VectorSelector)
 			vs.PosRange = mergeRanges(&yyDollar[1].item, vs)
@@ -1193,9 +1209,9 @@ yydefault:
 			yylex.(*parser).assembleVectorSelector(vs)
 			yyVAL.node = vs
 		}
-	case 74:
+	case 75:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:455
+//line promql/generated_parser.y:460
 		{
 			vs := &VectorSelector{
 				Name:          yyDollar[1].item.Val,
@@ -1205,228 +1221,241 @@ yydefault:
 			yylex.(*parser).assembleVectorSelector(vs)
 			yyVAL.node = vs
 		}
-	case 75:
+	case 76:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:465
+//line promql/generated_parser.y:470
 		{
 			vs := yyDollar[1].node.(*VectorSelector)
 			yylex.(*parser).assembleVectorSelector(vs)
 			yyVAL.node = vs
 		}
-	case 76:
+	case 77:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:473
+//line promql/generated_parser.y:478
 		{
 			yyVAL.node = &VectorSelector{
 				LabelMatchers: yyDollar[2].matchers,
 				PosRange:      mergeRanges(&yyDollar[1].item, &yyDollar[3].item),
 			}
 		}
-	case 77:
+	case 78:
 		yyDollar = yyS[yypt-4 : yypt+1]
-//line promql/generated_parser.y:480
+//line promql/generated_parser.y:485
 		{
 			yyVAL.node = &VectorSelector{
 				LabelMatchers: yyDollar[2].matchers,
 				PosRange:      mergeRanges(&yyDollar[1].item, &yyDollar[4].item),
 			}
 		}
-	case 78:
+	case 79:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:487
+//line promql/generated_parser.y:492
 		{
 			yyVAL.node = &VectorSelector{
 				LabelMatchers: []*labels.Matcher{},
 				PosRange:      mergeRanges(&yyDollar[1].item, &yyDollar[2].item),
 			}
 		}
-	case 79:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:496
-		{
-			yyVAL.matchers = append(yyDollar[1].matchers, yyDollar[3].matcher)
-		}
 	case 80:
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:501
+		{
+			if yyDollar[1].matchers != nil {
+				yyVAL.matchers = append(yyDollar[1].matchers, yyDollar[3].matcher)
+			} else {
+				yyVAL.matchers = yyDollar[1].matchers
+			}
+		}
+	case 81:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:498
+//line promql/generated_parser.y:509
 		{
 			yyVAL.matchers = []*labels.Matcher{yyDollar[1].matcher}
 		}
-	case 81:
+	case 82:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:500
+//line promql/generated_parser.y:511
 		{
 			yylex.(*parser).unexpected("label matching", "\",\" or \"}\"")
-		}
-	case 82:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:504
-		{
-			yyVAL.matcher = yylex.(*parser).newLabelMatcher(yyDollar[1].item, yyDollar[2].item, yyDollar[3].item)
+			yyVAL.matchers = yyDollar[1].matchers
 		}
 	case 83:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:506
+//line promql/generated_parser.y:515
 		{
-			yylex.(*parser).unexpected("label matching", "string")
+			yyVAL.matcher = yylex.(*parser).newLabelMatcher(yyDollar[1].item, yyDollar[2].item, yyDollar[3].item)
 		}
 	case 84:
-		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:508
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:517
 		{
-			yylex.(*parser).unexpected("label matching", "label matching operator")
+			yylex.(*parser).unexpected("label matching", "string")
+			yyVAL.matcher = nil
 		}
 	case 85:
-		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:510
+		yyDollar = yyS[yypt-2 : yypt+1]
+//line promql/generated_parser.y:519
 		{
-			yylex.(*parser).unexpected("label matching", "identifier or \"}\"")
+			yylex.(*parser).unexpected("label matching", "label matching operator")
+			yyVAL.matcher = nil
 		}
 	case 86:
+		yyDollar = yyS[yypt-1 : yypt+1]
+//line promql/generated_parser.y:521
+		{
+			yylex.(*parser).unexpected("label matching", "identifier or \"}\"")
+			yyVAL.matcher = nil
+		}
+	case 87:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:518
+//line promql/generated_parser.y:529
 		{
 			yyVAL.labels = append(yyDollar[2].labels, labels.Label{Name: labels.MetricName, Value: yyDollar[1].item.Val})
 			sort.Sort(yyVAL.labels)
 		}
-	case 87:
+	case 88:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:520
+//line promql/generated_parser.y:531
 		{
 			yyVAL.labels = yyDollar[1].labels
 		}
-	case 90:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:527
-		{
-			yyVAL.labels = labels.New(yyDollar[2].labels...)
-		}
 	case 91:
-		yyDollar = yyS[yypt-4 : yypt+1]
-//line promql/generated_parser.y:529
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:538
 		{
 			yyVAL.labels = labels.New(yyDollar[2].labels...)
 		}
 	case 92:
-		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:531
+		yyDollar = yyS[yypt-4 : yypt+1]
+//line promql/generated_parser.y:540
 		{
-			yyVAL.labels = labels.New()
+			yyVAL.labels = labels.New(yyDollar[2].labels...)
 		}
 	case 93:
-		yyDollar = yyS[yypt-0 : yypt+1]
-//line promql/generated_parser.y:533
+		yyDollar = yyS[yypt-2 : yypt+1]
+//line promql/generated_parser.y:542
 		{
 			yyVAL.labels = labels.New()
 		}
 	case 94:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:537
+		yyDollar = yyS[yypt-0 : yypt+1]
+//line promql/generated_parser.y:544
 		{
-			yyVAL.labels = append(yyDollar[1].labels, yyDollar[3].label)
+			yyVAL.labels = labels.New()
 		}
 	case 95:
-		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:539
-		{
-			yyVAL.labels = []labels.Label{yyDollar[1].label}
-		}
-	case 96:
-		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:541
-		{
-			yylex.(*parser).unexpected("label set", "\",\" or \"}\"")
-		}
-	case 97:
-		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:546
-		{
-			yyVAL.label = labels.Label{Name: yyDollar[1].item.Val, Value: yylex.(*parser).unquoteString(yyDollar[3].item.Val)}
-		}
-	case 98:
 		yyDollar = yyS[yypt-3 : yypt+1]
 //line promql/generated_parser.y:548
 		{
-			yylex.(*parser).unexpected("label set", "string")
+			yyVAL.labels = append(yyDollar[1].labels, yyDollar[3].label)
 		}
-	case 99:
-		yyDollar = yyS[yypt-2 : yypt+1]
+	case 96:
+		yyDollar = yyS[yypt-1 : yypt+1]
 //line promql/generated_parser.y:550
 		{
-			yylex.(*parser).unexpected("label set", "\"=\"")
+			yyVAL.labels = []labels.Label{yyDollar[1].label}
 		}
-	case 100:
-		yyDollar = yyS[yypt-1 : yypt+1]
+	case 97:
+		yyDollar = yyS[yypt-2 : yypt+1]
 //line promql/generated_parser.y:552
 		{
-			yylex.(*parser).unexpected("label set", "identifier or \"}\"")
+			yylex.(*parser).unexpected("label set", "\",\" or \"}\"")
+			yyVAL.labels = yyDollar[1].labels
+		}
+	case 98:
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:557
+		{
+			yyVAL.label = labels.Label{Name: yyDollar[1].item.Val, Value: yylex.(*parser).unquoteString(yyDollar[3].item.Val)}
+		}
+	case 99:
+		yyDollar = yyS[yypt-3 : yypt+1]
+//line promql/generated_parser.y:559
+		{
+			yylex.(*parser).unexpected("label set", "string")
+			yyVAL.label = labels.Label{}
+		}
+	case 100:
+		yyDollar = yyS[yypt-2 : yypt+1]
+//line promql/generated_parser.y:561
+		{
+			yylex.(*parser).unexpected("label set", "\"=\"")
+			yyVAL.label = labels.Label{}
 		}
 	case 101:
+		yyDollar = yyS[yypt-1 : yypt+1]
+//line promql/generated_parser.y:563
+		{
+			yylex.(*parser).unexpected("label set", "identifier or \"}\"")
+			yyVAL.label = labels.Label{}
+		}
+	case 102:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:560
+//line promql/generated_parser.y:571
 		{
 			yylex.(*parser).generatedParserResult = &seriesDescription{
 				labels: yyDollar[1].labels,
 				values: yyDollar[2].series,
 			}
 		}
-	case 102:
+	case 103:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line promql/generated_parser.y:569
+//line promql/generated_parser.y:580
 		{
 			yyVAL.series = []sequenceValue{}
 		}
-	case 103:
+	case 104:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:571
+//line promql/generated_parser.y:582
 		{
 			yyVAL.series = append(yyDollar[1].series, yyDollar[3].series...)
 		}
-	case 104:
+	case 105:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:573
+//line promql/generated_parser.y:584
 		{
 			yyVAL.series = yyDollar[1].series
 		}
-	case 105:
-		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:575
-		{
-			yylex.(*parser).unexpected("series values", "")
-		}
 	case 106:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:579
+//line promql/generated_parser.y:586
+		{
+			yylex.(*parser).unexpected("series values", "")
+			yyVAL.series = nil
+		}
+	case 107:
+		yyDollar = yyS[yypt-1 : yypt+1]
+//line promql/generated_parser.y:590
 		{
 			yyVAL.series = []sequenceValue{{omitted: true}}
 		}
-	case 107:
+	case 108:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:581
+//line promql/generated_parser.y:592
 		{
 			yyVAL.series = []sequenceValue{}
 			for i := uint64(0); i < yyDollar[3].uint; i++ {
 				yyVAL.series = append(yyVAL.series, sequenceValue{omitted: true})
 			}
 		}
-	case 108:
+	case 109:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:588
+//line promql/generated_parser.y:599
 		{
 			yyVAL.series = []sequenceValue{{value: yyDollar[1].float}}
 		}
-	case 109:
+	case 110:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line promql/generated_parser.y:590
+//line promql/generated_parser.y:601
 		{
 			yyVAL.series = []sequenceValue{}
 			for i := uint64(0); i <= yyDollar[3].uint; i++ {
 				yyVAL.series = append(yyVAL.series, sequenceValue{value: yyDollar[1].float})
 			}
 		}
-	case 110:
+	case 111:
 		yyDollar = yyS[yypt-4 : yypt+1]
-//line promql/generated_parser.y:597
+//line promql/generated_parser.y:608
 		{
 			yyVAL.series = []sequenceValue{}
 			for i := uint64(0); i <= yyDollar[4].uint; i++ {
@@ -1434,45 +1463,45 @@ yydefault:
 				yyDollar[1].float += yyDollar[2].float
 			}
 		}
-	case 111:
+	case 112:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:607
+//line promql/generated_parser.y:618
 		{
 			if yyDollar[1].item.Val != "stale" {
 				yylex.(*parser).unexpected("series values", "number or \"stale\"")
 			}
 			yyVAL.float = math.Float64frombits(value.StaleNaN)
 		}
-	case 154:
+	case 155:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:638
+//line promql/generated_parser.y:649
 		{
 			yyVAL.node = &NumberLiteral{
 				Val:      yylex.(*parser).number(yyDollar[1].item.Val),
 				PosRange: yyDollar[1].item.PositionRange(),
 			}
 		}
-	case 155:
+	case 156:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:646
+//line promql/generated_parser.y:657
 		{
 			yyVAL.float = yylex.(*parser).number(yyDollar[1].item.Val)
 		}
-	case 156:
+	case 157:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:648
+//line promql/generated_parser.y:659
 		{
 			yyVAL.float = yyDollar[2].float
 		}
-	case 157:
+	case 158:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line promql/generated_parser.y:649
+//line promql/generated_parser.y:660
 		{
 			yyVAL.float = -yyDollar[2].float
 		}
-	case 158:
+	case 159:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:653
+//line promql/generated_parser.y:664
 		{
 			var err error
 			yyVAL.uint, err = strconv.ParseUint(yyDollar[1].item.Val, 10, 64)
@@ -1480,9 +1509,9 @@ yydefault:
 				yylex.(*parser).failf(yyDollar[1].item.PositionRange(), "invalid repetition in series values: %s", err)
 			}
 		}
-	case 159:
+	case 160:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:663
+//line promql/generated_parser.y:674
 		{
 			var err error
 			yyVAL.duration, err = parseDuration(yyDollar[1].item.Val)
@@ -1490,24 +1519,24 @@ yydefault:
 				yylex.(*parser).fail(yyDollar[1].item.PositionRange(), err)
 			}
 		}
-	case 160:
+	case 161:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line promql/generated_parser.y:674
+//line promql/generated_parser.y:685
 		{
 			yyVAL.node = &StringLiteral{
 				Val:      yylex.(*parser).unquoteString(yyDollar[1].item.Val),
 				PosRange: yyDollar[1].item.PositionRange(),
 			}
 		}
-	case 161:
+	case 162:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line promql/generated_parser.y:687
+//line promql/generated_parser.y:698
 		{
 			yyVAL.duration = 0
 		}
-	case 163:
+	case 164:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line promql/generated_parser.y:691
+//line promql/generated_parser.y:702
 		{
 			yyVAL.strings = nil
 		}
diff --git a/promql/parse.go b/promql/parse.go
index 2a6cd29d74..03494662da 100644
--- a/promql/parse.go
+++ b/promql/parse.go
@@ -48,11 +48,10 @@ type parser struct {
 	yyParser yyParserImpl
 
 	generatedParserResult interface{}
+	parseErrors           ParseErrors
 }
 
 // ParseErr wraps a parsing error with line and position context.
-// If the parsing input was a single line, line will be 0 and omitted
-// from the error string.
 type ParseErr struct {
 	PositionRange PositionRange
 	Err           error
@@ -86,14 +85,43 @@ func (e *ParseErr) Error() string {
 	return fmt.Sprintf("%s parse error: %s", positionStr, e.Err)
 }
 
+type ParseErrors []ParseErr
+
+// Since producing multiple error messages might look weird when combined with error wrapping,
+// only the first error produced by the parser is included in the error string.
+// If getting the full error list is desired, it is recommended to typecast the error returned
+// by the parser to ParseErrors and work with the underlying slice.
+func (errs ParseErrors) Error() string {
+	if len(errs) != 0 {
+		return errs[0].Error()
+	} else {
+		// Should never happen
+		// Panicking while printing an error seems like a bad idea, so the
+		// situation is explained in the error message instead.
+		return "error contains no error message"
+	}
+}
+
 // ParseExpr returns the expression parsed from the input.
 func ParseExpr(input string) (expr Expr, err error) {
 	p := newParser(input)
 	defer parserPool.Put(p)
 	defer p.recover(&err)
 
-	expr = p.parseGenerated(START_EXPRESSION).(Expr)
-	err = p.typecheck(expr)
+	parseResult := p.parseGenerated(START_EXPRESSION)
+
+	if parseResult != nil {
+		expr = parseResult.(Expr)
+	}
+
+	// Only typecheck when there are no syntax errors.
+	if len(p.parseErrors) == 0 {
+		p.checkType(expr)
+	}
+
+	if len(p.parseErrors) != 0 {
+		err = p.parseErrors
+	}
 
 	return expr, err
 }
@@ -104,7 +132,16 @@ func ParseMetric(input string) (m labels.Labels, err error) {
 	defer parserPool.Put(p)
 	defer p.recover(&err)
 
-	return p.parseGenerated(START_METRIC).(labels.Labels), nil
+	parseResult := p.parseGenerated(START_METRIC)
+	if parseResult != nil {
+		m = parseResult.(labels.Labels)
+	}
+
+	if len(p.parseErrors) != 0 {
+		err = p.parseErrors
+	}
+
+	return m, err
 }
 
 // ParseMetricSelector parses the provided textual metric selector into a list of
@@ -114,7 +151,16 @@ func ParseMetricSelector(input string) (m []*labels.Matcher, err error) {
 	defer parserPool.Put(p)
 	defer p.recover(&err)
 
-	return p.parseGenerated(START_METRIC_SELECTOR).(*VectorSelector).LabelMatchers, nil
+	parseResult := p.parseGenerated(START_METRIC_SELECTOR)
+	if parseResult != nil {
+		m = parseResult.(*VectorSelector).LabelMatchers
+	}
+
+	if len(p.parseErrors) != 0 {
+		err = p.parseErrors
+	}
+
+	return m, err
 }
 
 // newParser returns a new parser.
@@ -122,6 +168,7 @@ func newParser(input string) *parser {
 	p := parserPool.Get().(*parser)
 
 	p.injecting = false
+	p.parseErrors = nil
 
 	// Clear lexer struct before reusing.
 	p.lex = Lexer{
@@ -151,27 +198,26 @@ type seriesDescription struct {
 
 // parseSeriesDesc parses the description of a time series.
 func parseSeriesDesc(input string) (labels labels.Labels, values []sequenceValue, err error) {
-
 	p := newParser(input)
 	p.lex.seriesDesc = true
 
 	defer parserPool.Put(p)
 	defer p.recover(&err)
 
-	result := p.parseGenerated(START_SERIES_DESCRIPTION).(*seriesDescription)
+	parseResult := p.parseGenerated(START_SERIES_DESCRIPTION)
+	if parseResult != nil {
+		result := parseResult.(*seriesDescription)
 
-	labels = result.labels
-	values = result.values
+		labels = result.labels
+		values = result.values
 
-	return
-}
+	}
 
-// typecheck checks correct typing of the parsed statements or expression.
-func (p *parser) typecheck(node Node) (err error) {
-	defer p.recover(&err)
+	if len(p.parseErrors) != 0 {
+		err = p.parseErrors
+	}
 
-	p.checkType(node)
-	return nil
+	return labels, values, err
 }
 
 // failf formats the error and terminates processing.
@@ -181,12 +227,13 @@ func (p *parser) failf(positionRange PositionRange, format string, args ...inter
 
 // fail terminates processing.
 func (p *parser) fail(positionRange PositionRange, err error) {
-	perr := &ParseErr{
+	perr := ParseErr{
 		PositionRange: positionRange,
 		Err:           err,
 		Query:         p.lex.input,
 	}
-	panic(perr)
+
+	p.parseErrors = append(p.parseErrors, perr)
 }
 
 // unexpected creates a parser error complaining about an unexpected lexer item.
@@ -258,6 +305,7 @@ func (p *parser) Lex(lval *yySymType) int {
 
 	case ERROR:
 		p.failf(lval.item.PositionRange(), "%s", lval.item.Val)
+		p.InjectItem(0)
 	case EOF:
 		lval.item.Typ = EOF
 		p.InjectItem(0)
@@ -340,7 +388,7 @@ func (p *parser) assembleVectorSelector(vs *VectorSelector) {
 	if vs.Name != "" {
 
 		for _, m := range vs.LabelMatchers {
-			if m.Name == labels.MetricName {
+			if m != nil && m.Name == labels.MetricName {
 				p.failf(vs.PositionRange(), "metric name must not be set twice: %q or %q", vs.Name, m.Value)
 			}
 		}
@@ -356,7 +404,7 @@ func (p *parser) assembleVectorSelector(vs *VectorSelector) {
 	// implicit selection of all metrics (e.g. by a typo).
 	notEmpty := false
 	for _, lm := range vs.LabelMatchers {
-		if !lm.Matches("") {
+		if lm != nil && !lm.Matches("") {
 			notEmpty = true
 			break
 		}
diff --git a/promql/parse_test.go b/promql/parse_test.go
index ffeaff210b..9bd6e57df4 100644
--- a/promql/parse_test.go
+++ b/promql/parse_test.go
@@ -1963,6 +1963,10 @@ var testExpr = []struct {
 		input:  `topk(some_metric)`,
 		fail:   true,
 		errMsg: "wrong number of arguments for aggregate expression provided, expected 2, got 1",
+	}, {
+		input:  `topk(some_metric,)`,
+		fail:   true,
+		errMsg: "trailing commas not allowed in function call args",
 	}, {
 		input:  `topk(some_metric, other_metric)`,
 		fail:   true,