diff --git a/compat/compat.c b/compat/compat.c
index 1ae54f6..0ed350a 100644
--- a/compat/compat.c
+++ b/compat/compat.c
@@ -128,7 +128,7 @@
 {
     static char line[256];
     char *ptr;
-    unsigned int len;
+    ssize_t len;
 
     if (!lineptr || !n) {
         errno = EINVAL;