diff --git a/sc2/build/build.sh b/sc2/build/build.sh
index 7bf01dfae..34d52a858 100644
--- a/sc2/build/build.sh
+++ b/sc2/build/build.sh
@@ -29,7 +29,7 @@ if [ -e build.vars -a -z "$BUILD_COMMAND" ]; then
 fi
 
 # Read in the Makeinfo file for the dir currently being processed
-. "${BUILD_REC_PATH:./}Makeinfo"
+. "${BUILD_REC_PATH:=./}Makeinfo"
 
 # If we're recursing, go on.
 if [ -n "$BUILD_COMMAND" ]; then