diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3374b1cc4..7ee5f5681 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -246,6 +246,8 @@ fedora meson build:
     - (cd doc/public && bash "check-doc-syntax.sh")
     # FIXME: The following line really needs gtk-doc to run first
     - (cd doc/public && DOC_MODULE=cairo bash "check-doc-coverage.sh")
+    # Check for duplicate reference images
+    - ./test/check-refs.sh "$(pwd)/builddir/test/pdiff/perceptualdiff"
 
     - ninja -C builddir install
   artifacts:
diff --git a/test/check-refs.sh b/test/check-refs.sh
index 81ef81b35..e2e8a1a2a 100755
--- a/test/check-refs.sh
+++ b/test/check-refs.sh
@@ -9,6 +9,8 @@ if [ ! -e "${pdiff}" ]; then
     exit 128
 fi
 
+exit_code=0
+
 for file in *.ref.png; do
     test=$(echo $file | cut -d'.' -f1)
     target=$(echo $file | cut -d'.' -f2)
@@ -48,6 +50,7 @@ for file in *.ref.png; do
     if [ -e $ref ]; then
 	if cmp --silent "$ref" "$file" ; then
 	    printf "redundant: %s and %s are byte-by-byte identical files\n" $file $ref
+	    exit_code=1
 	else
             # Run perceptualdiff with minimum threshold
             pdiff_output=$($pdiff $ref $file -threshold 1)
@@ -55,9 +58,12 @@ for file in *.ref.png; do
             notes=$(echo "${pdiff_output#*: }" | tail -n 1)
             if [ "$result" = "PASS" ] && [ "$notes" = "Images are binary identical" ]; then
 		printf "redundant: %s and %s are pixel equivalent images\n" $file $ref
+		exit_code=1
 		notes=""
             fi
 	fi
     fi
 
 done
+
+exit $exit_code