diff --git a/src/findfile.c b/src/findfile.c
index 4f457b9..ab59776 100644
--- a/src/findfile.c
+++ b/src/findfile.c
@@ -2653,7 +2653,7 @@
 
     p = filename;
 # ifdef BACKSLASH_IN_FILENAME
-    if (p[1] == ':')	    // skip "x:"
+    if (p[0] != NUL && p[1] == ':')	    // skip "x:"
 	p += 2;
 # endif