diff --git a/lib/test_fortify/test_fortify.sh b/lib/test_fortify/test_fortify.sh
index c2688ab8281d..368d07d9acbf 100644
--- a/lib/test_fortify/test_fortify.sh
+++ b/lib/test_fortify/test_fortify.sh
@@ -17,7 +17,7 @@ WANT="__${FILE%%-*}"
 # Argument 2: Where to write the build log.
 OUT="$1"
 shift
-TMP="${OUT}.tmp"
+TMP="${OUT%/*}/.${OUT##*/}.tmp"
 
 # Argument 3: Path to "nm" tool.
 NM="$1"