diff --git a/src/os_mswin.c b/src/os_mswin.c
index 374a239..8154549 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -453,8 +453,9 @@
 
     if (*p == '`')
     {
+	size_t len = STRLEN(p);
+
 	/* don't replace backslash in backtick quoted strings */
-	int len = STRLEN(p);
 	if (len > 2 && *(p + len - 1) == '`')
 	    return;
     }