diff --git a/internal/kokoro/check_incompat_changes.sh b/internal/kokoro/check_incompat_changes.sh
index 62533190c56ea1681916dbaa6961807cec3ca89c..c185f3eaa7d4de3caa6960307439820d48ceb27c 100755
--- a/internal/kokoro/check_incompat_changes.sh
+++ b/internal/kokoro/check_incompat_changes.sh
@@ -34,8 +34,8 @@ for dir in $V1_DIRS $V1_SUBDIRS; do
 
   # TODO(deklerk) there's probably a nicer way to do this that doesn't require
   # two invocations
-  if ! apidiff /tmp/pkg.master $pkg | (! read); then
-    apidiff /tmp/pkg.master $pkg
+  if ! apidiff -incompatible /tmp/pkg.master $pkg | (! read); then
+    apidiff -incompatible /tmp/pkg.master $pkg
     exit 1
   fi
 done