diff --git a/char32.c b/char32.c
index 97c599d9..827cef8d 100644
--- a/char32.c
+++ b/char32.c
@@ -176,7 +176,7 @@ done:
     return chars;
 
 err:
-    return (char32_t)-1;
+    return (size_t)-1;
 }
 
 UNITTEST