diff --git a/.travis.yml b/.travis.yml
index bf71152..4f474e6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ sudo: required
 dist: trusty
 
 go:
-  - 1.9.2
+  - 1.13
 
 env:
   - DOCKER_TAG=$TRAVIS_TAG
diff --git a/Dockerfile b/Dockerfile
index 0c03bec..6c9ebd1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,7 +17,7 @@ RUN apt-get update && \
 
 RUN \
   mkdir -p /goroot && \
-  curl https://storage.googleapis.com/golang/go1.9.2.linux-amd64.tar.gz | tar xvzf - -C /goroot --strip-components=1
+  curl https://storage.googleapis.com/golang/go1.13.linux-amd64.tar.gz | tar xvzf - -C /goroot --strip-components=1
 
 ADD . $APPLOC
 WORKDIR $APPLOC
diff --git a/Makefile.COMMON b/Makefile.COMMON
index f8aa1b3..9198cf9 100644
--- a/Makefile.COMMON
+++ b/Makefile.COMMON
@@ -44,7 +44,7 @@ SRC    ?= $(shell find . -type f -name "*.go" ! -path "./.build/*")
 GOOS   ?= $(shell uname | tr A-Z a-z)
 GOARCH ?= $(subst x86_64,amd64,$(patsubst i%86,386,$(shell uname -m)))
 
-GO_VERSION ?= 1.5.3
+GO_VERSION ?= 1.13
 
 # Check for the correct version of go in the path. If we find it, use it.
 # Otherwise, prepare to build go locally.
diff --git a/collectors/osd.go b/collectors/osd.go
index 5d38373..8c76ef2 100644
--- a/collectors/osd.go
+++ b/collectors/osd.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"math"
 	"regexp"
 	"strconv"
 
@@ -820,11 +821,11 @@ func (o *OSDCollector) collectPGRecoveryState(ch chan<- prometheus.Metric) error
 		// We need previous PG state in order to update the metric when a PG has
 		// completed recovery or backfill. Or it could be an empty string if
 		// unknown.
-		prevPGState := o.pgStateCache[pg.PGID]
+		prevPGState, prevPGStateFound := o.pgStateCache[pg.PGID]
 		prevNumObjectsRecovered := o.pgObjectsRecoveredCache[pg.PGID]
 		prevBackfillTargets := o.pgBackfillTargetsCache[pg.PGID]
 
-		if prevPGState == "" || strings.Contains(prevPGState, "recovering") || strings.Contains(pg.State, "recovering") ||
+		if !prevPGStateFound || strings.Contains(prevPGState, "recovering") || strings.Contains(pg.State, "recovering") ||
 			strings.Contains(prevPGState, "backfilling") || strings.Contains(pg.State, "backfilling") {
 			query, err := o.performPGQuery(pg.PGID)
 			if err != nil {
@@ -845,7 +846,9 @@ func (o *OSDCollector) collectPGRecoveryState(ch chan<- prometheus.Metric) error
 			}
 
 			// Average out the total number of objects backfilled to each OSD
-			eachOSDIncrease := float64(o.pgObjectsRecoveredCache[pg.PGID]-prevNumObjectsRecovered) / float64(len(prevBackfillTargets))
+			// The average number rounds to the nearest integer, rounding half
+			// away from zero.
+			eachOSDIncrease := math.Round(float64(o.pgObjectsRecoveredCache[pg.PGID]-prevNumObjectsRecovered) / float64(len(prevBackfillTargets)))
 
 			for osdID := range prevBackfillTargets {
 				// It is possible that osdID has gone from the backfill_targets