diff --git a/contrib/instrumentation.sh b/contrib/instrumentation.sh
index b8ac5841d..6ab3998c5 100644
--- a/contrib/instrumentation.sh
+++ b/contrib/instrumentation.sh
@@ -14,8 +14,8 @@ do
     adb logcat -c
     adb logcat ./*:E -v color &
     ./gradlew clean
-    retry=$(( $retry + 1 ))
-    if [ $retry == 3 ]; then
+    retry=$(( retry + 1 ))
+    if [ $retry -eq 3 ]; then
       adb exec-out screencap -p >screencap.png
       exit 1
     fi