diff --git a/libc/stdio/stdio_ext.cpp b/libc/stdio/stdio_ext.cpp
index e17b62a..945813e 100644
--- a/libc/stdio/stdio_ext.cpp
+++ b/libc/stdio/stdio_ext.cpp
@@ -69,7 +69,7 @@
 
 void _flushlbf() {
   // If we flush all streams, we know we've flushed all the line-buffered streams.
-  fflush(NULL);
+  fflush(nullptr);
 }
 
 void __fseterr(FILE* fp) {