diff --git a/tests/hwsim/run-all.sh b/tests/hwsim/run-all.sh
index ee48cd058..7c50edd79 100755
--- a/tests/hwsim/run-all.sh
+++ b/tests/hwsim/run-all.sh
@@ -15,7 +15,11 @@ export LOGDIR
 if [ -z "$DBFILE" ]; then
     DB=""
 else
-    DB="-S $DBFILE --commit $(git rev-parse HEAD)"
+    DB="-S $DBFILE"
+    COMMITID="$(git rev-parse HEAD)"
+    if [ -n "$COMMITID" ]; then
+	DB="$DB --commit $COMMITID"
+    fi
     if [ -n "$BUILD" ]; then
 	DB="$DB -b $BUILD"
     fi