1 files changed, 4 insertions, 2 deletions
diff --git a/osdep/io.h b/osdep/io.h
index 5dd93a79a1..d855e852eb 100644
--- a/osdep/io.h
+++ b/osdep/io.h
@@ -43,9 +43,11 @@ char *mp_to_utf8(void *talloc_ctx, const wchar_t *s);
 // applies to unicode paths encoded with wchar_t (2 bytes on Windows). The UTF-8
 // version could end up bigger in memory. In the worst case each wchar_t is
 // encoded to 3 bytes in UTF-8, so in the worst case we have:
-//      wcslen(wpath) <= strlen(utf8path) * 3
+//      wcslen(wpath) * 3 <= strlen(utf8path)
 // Thus we need MP_PATH_MAX as the UTF-8/char version of PATH_MAX.
-#define MP_PATH_MAX (FILENAME_MAX * 3)
+// Also make sure there's free space for the terminating \0.
+// (For codepoints encoded as UTF-16 surrogate pairs, UTF-8 has the same length.)
+#define MP_PATH_MAX (FILENAME_MAX * 3 + 1)
 
 void mp_get_converted_argv(int *argc, char ***argv);