diff --git a/scripts/pgit.sh b/scripts/pgit.sh
index b7700ecb..aa2163ba 100644
--- a/scripts/pgit.sh
+++ b/scripts/pgit.sh
@@ -78,7 +78,7 @@ set_global_variables()
 		# If we're in a toplevel directory, suppose projects_dir == project_dirs,
 		# i.e. we only want to target this Git repo
 		if [ ! -d .git ]; then
-			while [ ! -r Makefile ] || ! grep -q some-random-string-to-id-this-makefile Makefile; do
+			while [ ! -r Makefile ] || ! grep -q 'include $(JWBDIR)/make/projects-dir\.mk\|some-random-string-to-id-this-makefile' Makefile; do
 				[ "$projects_dir" = / ] && fatal "Failed to find projects directory"
 				projects_dir=`dirname $projects_dir`
 			done