diff --git a/src/sample.c b/src/sample.c
index b3d28cab55..b124c4b861 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -921,6 +921,8 @@ struct sample_expr *sample_parse_expr(char **str, int *idx, const char *file, in
 
 	while (1) {
 		struct sample_conv_expr *conv_expr;
+		int err_arg;
+		int argcnt;
 
 		if (*endt == ')') /* skip last closing parenthesis */
 			endt++;
@@ -963,6 +965,7 @@ struct sample_expr *sample_parse_expr(char **str, int *idx, const char *file, in
 		endt = endw;
 		if (*endt == '(') {
 			/* look for the end of this term */
+			endt = ++endw;
 			while (*endt && *endt != ')')
 				endt++;
 			if (*endt != ')') {
@@ -990,31 +993,24 @@ struct sample_expr *sample_parse_expr(char **str, int *idx, const char *file, in
 		LIST_ADDQ(&(expr->conv_exprs), &(conv_expr->list));
 		conv_expr->conv = conv;
 
-		if (endt != endw) {
-			int err_arg;
-
-			if (!conv->arg_mask) {
-				memprintf(err_msg, "converter '%s' does not support any args", ckw);
-				goto out_error;
-			}
-
-			al->kw = expr->fetch->kw;
-			al->conv = conv_expr->conv->kw;
-			if (make_arg_list(endw + 1, endt - endw - 1, conv->arg_mask, &conv_expr->arg_p, err_msg, NULL, &err_arg, al) < 0) {
-				memprintf(err_msg, "invalid arg %d in converter '%s' : %s", err_arg+1, ckw, *err_msg);
-				goto out_error;
-			}
-
-			if (!conv_expr->arg_p)
-				conv_expr->arg_p = empty_arg_list;
-
-			if (conv->val_args && !conv->val_args(conv_expr->arg_p, conv, file, line, err_msg)) {
-				memprintf(err_msg, "invalid args in converter '%s' : %s", ckw, *err_msg);
-				goto out_error;
-			}
+		al->kw = expr->fetch->kw;
+		al->conv = conv_expr->conv->kw;
+		argcnt = make_arg_list(endw, endt - endw, conv->arg_mask, &conv_expr->arg_p, err_msg, NULL, &err_arg, al);
+		if (argcnt < 0) {
+			memprintf(err_msg, "invalid arg %d in converter '%s' : %s", err_arg+1, ckw, *err_msg);
+			goto out_error;
 		}
-		else if (ARGM(conv->arg_mask)) {
-			memprintf(err_msg, "missing args for converter '%s'", ckw);
+
+		if (argcnt && !conv->arg_mask) {
+			memprintf(err_msg, "converter '%s' does not support any args", ckw);
+			goto out_error;
+		}
+
+		if (!conv_expr->arg_p)
+			conv_expr->arg_p = empty_arg_list;
+
+		if (conv->val_args && !conv->val_args(conv_expr->arg_p, conv, file, line, err_msg)) {
+			memprintf(err_msg, "invalid args in converter '%s' : %s", ckw, *err_msg);
 			goto out_error;
 		}
 	}