diff --git a/conf/layer.conf b/conf/layer.conf
index 74ebe9d..65c8b35 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -23,3 +23,6 @@ SIGGEN_EXCLUDERECIPES_ABISAFE += "\
 
 # Needed for external_run() for PV & LICENSE in the recipes, to be able to parse
 INHERIT_append = " external-common"
+
+# Fallback default for when the tcmode isn't sourced
+GCC_VERSION ?= "0.0"