diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index 7596a9d9..9be13eea 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -27,6 +27,9 @@ extern FILE* stderr;
 #define stderr stderr
 
 #define BUFSIZ 1024
+#define FILENAME_MAX                                                                                                   \
+    1024 // As Luna does not impose a limit on this, this is the recommended size for character arrays holding a file
+         // name.
 
 #ifdef __cplusplus
 extern "C"