diff --git a/xcode/build_phases/api_generator.sh b/xcode/build_phases/api_generator.sh
index 3ea2951..26210ec 100755
--- a/xcode/build_phases/api_generator.sh
+++ b/xcode/build_phases/api_generator.sh
@@ -76,12 +76,12 @@ get_api_spec_current_commit()
 {
     if [ -z "${API_SPEC_DIR}" ]; then
         if [ ! -z "${1}" ]; then
-            echo `git rev-parse HEAD:${1}`
+            echo `git -C ${1} rev-parse --verify HEAD`
         else
-            echo `git rev-parse HEAD`
+            echo `git rev-parse --verify HEAD`
         fi
     else
-        echo `git rev-parse HEAD:${API_SPEC_DIR}`
+        echo `git -C ${API_SPEC_DIR} rev-parse --verify HEAD`
     fi
 }
 
@@ -114,7 +114,7 @@ is_nothing_changed_since_last_check()
         fi
     fi
 
-    if [ is_api_spec_under_source_control == "true" ]; then
+    if [ `is_api_spec_under_source_control` == "true" ]; then
         local -r CURRENT_COMMIT=`get_api_spec_current_commit`
 
         local -r LAST_CHECKED_COMMIT=`cat ${COMMIT_FILE_PATH} 2> /dev/null || echo ""`