diff --git a/build_tools/format-diff.sh b/build_tools/format-diff.sh
index 62e8834f7d..9dc85496c9 100755
--- a/build_tools/format-diff.sh
+++ b/build_tools/format-diff.sh
@@ -137,11 +137,11 @@ then
   # should be relevant for formatting fixes.
   FORMAT_UPSTREAM_MERGE_BASE="$(git merge-base "$FORMAT_UPSTREAM" HEAD)"
   # Get the differences
-  diffs=$(git diff -U0 "$FORMAT_UPSTREAM_MERGE_BASE" | $CLANG_FORMAT_DIFF -p 1)
+  diffs=$(git diff -U0 "$FORMAT_UPSTREAM_MERGE_BASE" | $CLANG_FORMAT_DIFF -p 1) || true
   echo "Checking format of changes not yet in $FORMAT_UPSTREAM..."
 else
   # Check the format of uncommitted lines,
-  diffs=$(git diff -U0 HEAD | $CLANG_FORMAT_DIFF -p 1)
+  diffs=$(git diff -U0 HEAD | $CLANG_FORMAT_DIFF -p 1) || true
   echo "Checking format of uncommitted changes..."
 fi
 
@@ -149,6 +149,9 @@ if [ -z "$diffs" ]
 then
   echo "Nothing needs to be reformatted!"
   exit 0
+elif [ $? -ne 1 ]; then
+  # CLANG_FORMAT_DIFF will exit on 1 while there is suggested changes.
+  exit $?
 elif [ $CHECK_ONLY ]
 then
   echo "Your change has unformatted code. Please run make format!"