diff --git a/sc2/src/libs/file/dirs.c b/sc2/src/libs/file/dirs.c
index 2663edf70..4b2c5f65c 100644
--- a/sc2/src/libs/file/dirs.c
+++ b/sc2/src/libs/file/dirs.c
@@ -656,7 +656,7 @@ err:
 		// This code is only needed if we have a current working directory
 		// per drive.
 // letter is 0 based: 0 = A, 1 = B, ...
-bool
+static bool
 driveLetterExists(int letter)
 {
 	unsigned long drives;