diff --git a/src/ex_getln.c b/src/ex_getln.c
index 85f8cfa..561ab97 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -5025,7 +5025,7 @@
 
     *num_file = 0;
     *file = NULL;
-    pat_len = STRLEN(pat);
+    pat_len = (int)STRLEN(pat);
     ga_init2(&ga, (int)sizeof(char *), 10);
 
     for (i = 0; dirnames[i] != NULL; ++i)