diff --git a/kernel-open/conftest.sh b/kernel-open/conftest.sh
index 3b33a862d..65cb8173a 100755
--- a/kernel-open/conftest.sh
+++ b/kernel-open/conftest.sh
@@ -71,7 +71,8 @@ test_header_presence() {
     TEST_CFLAGS="-E -M $CFLAGS"
 
     file="$1"
-    file_define=NV_`echo $file | tr '/.\-a-z' '___A-Z'`_PRESENT
+    # Replace '.', '/', '-' with '_'
+    file_define=NV_`echo $file | awk '{ gsub(/\.|\/|-/, "_", $1); print toupper($0) }'`_PRESENT
 
     CODE="#include <$file>"