diff --git a/main.sh b/main.sh
index fca8661..2efac75 100755
--- a/main.sh
+++ b/main.sh
@@ -2,17 +2,15 @@
 
 set -eu
 
-echo "Entered main"
-
 BUILDER_IMAGE=$(printenv INPUT-BUILD-IMAGE)
 
 SRC_REPOSITORY=$(printenv INPUT-SRC-REPOSITORY)
-SRC_REF=$(printenv INPUT-SRC-REF:)
+SRC_REF=$(printenv INPUT-SRC-REF:-master)
 SRC_ACTOR=$(printenv INPUT-SRC-REF:-actions)
 SRC_TOKEN=$(printenv INPUT-SRC-TOKEN)
 
 DST_REPOSITORY=$(printenv INPUT-DST-REPOSITORY)
-DST_REF=$(printenv INPUT-DST-REF:)
+DST_REF=$(printenv INPUT-DST-REF:-master)
 DST_ACTOR=$(printenv INPUT-DST-REF:-actions)
 DST_TOKEN=$(printenv INPUT-DST-TOKEN)