diff --git a/autoninja b/autoninja
index 9e64c30bcd..d6e065f12d 100755
--- a/autoninja
+++ b/autoninja
@@ -10,7 +10,13 @@
 command=$(python $(dirname -- "$0")/autoninja.py "$@")
 echo $command
 $command
-if [ $? -eq 0 ] && [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
-  python $(dirname -- "$0")/post_build_ninja_summary.py $@
+if [ $? -eq 0 ]; then
+  if [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
+    python $(dirname -- "$0")/post_build_ninja_summary.py $@
+  fi
+  exit
 fi
+# Return an error code of 1 so that if a developer types:
+# "autoninja chrome && chrome" then chrome won't run if the build fails.
+exit 1
 
diff --git a/autoninja.bat b/autoninja.bat
index 5e1b6fe7c0..a071fb96ec 100755
--- a/autoninja.bat
+++ b/autoninja.bat
@@ -8,4 +8,8 @@ REM Also print it to reassure that the right settings are being used.
 FOR /f "usebackq tokens=*" %%a in (`python %~dp0autoninja.py "%*"`) do echo %%a & %%a
 @if errorlevel 1 goto buildfailure
 @if "%NINJA_SUMMARIZE_BUILD%" == "1" python %~dp0post_build_ninja_summary.py %*
+exit /b
 :buildfailure
+REM Return an error code of 1 so that if a developer types:
+REM "autoninja chrome && chrome" then chrome won't run if the build fails.
+cmd /c exit 1