diff --git a/lib/std/io/os/file_libc.c3 b/lib/std/io/os/file_libc.c3
index 30b878452..4eabe2133 100644
--- a/lib/std/io/os/file_libc.c3
+++ b/lib/std/io/os/file_libc.c3
@@ -77,7 +77,7 @@ fn usz! native_fwrite(CFile file, char[] buffer) @inline
 
 fn void! native_fputc(CInt c, CFile stream) @inline
 {
-	if (!libc::fputc(c, stream)) return IoError.EOF?;
+	if (libc::fputc(c, stream) == libc::EOF) return IoError.EOF?;
 }
 
 fn usz! native_fread(CFile file, char[] buffer) @inline