diff --git a/glib/dirent/dirent.c b/glib/dirent/dirent.c
index 26b6cb1e5..5b8f3ff80 100644
--- a/glib/dirent/dirent.c
+++ b/glib/dirent/dirent.c
@@ -135,7 +135,7 @@ _topendir (const _TCHAR *szPath)
   nd->dd_dir.d_ino = 0;
   nd->dd_dir.d_reclen = 0;
   nd->dd_dir.d_namlen = 0;
-  memset (nd->dd_dir.d_name, 0, FILENAME_MAX);
+  memset (nd->dd_dir.d_name, 0, sizeof (nd->dd_dir.d_name));
 
   return nd;
 }
diff --git a/glib/dirent/dirent.h b/glib/dirent/dirent.h
index 237665b4e..857710f6a 100644
--- a/glib/dirent/dirent.h
+++ b/glib/dirent/dirent.h
@@ -22,7 +22,7 @@ struct dirent
 	long		d_ino;		/* Always zero. */
 	unsigned short	d_reclen;	/* Always zero. */
 	unsigned short	d_namlen;	/* Length of name in d_name. */
-	char		d_name[FILENAME_MAX]; /* File name. */
+	char		d_name[FILENAME_MAX+1]; /* File name plus nul delimiter. */
 };
 
 #ifdef _WIN64
@@ -76,7 +76,7 @@ struct _wdirent
 	long		d_ino;		/* Always zero. */
 	unsigned short	d_reclen;	/* Always zero. */
 	unsigned short	d_namlen;	/* Length of name in d_name. */
-	wchar_t		d_name[FILENAME_MAX]; /* File name. */
+	wchar_t		d_name[FILENAME_MAX+1]; /* File name plus nul delimiter. */
 };
 
 /*
diff --git a/glib/gdir.c b/glib/gdir.c
index c26edc1dc..b07eb5c20 100644
--- a/glib/gdir.c
+++ b/glib/gdir.c
@@ -60,7 +60,9 @@ struct _GDir
   DIR *dirp;
 #endif
 #ifdef G_OS_WIN32
-  gchar utf8_buf[FILENAME_MAX*4];
+  /* maximum encoding of FILENAME_MAX UTF-8 characters, plus a nul terminator
+   * (FILENAME_MAX is not guaranteed to include one) */
+  gchar utf8_buf[FILENAME_MAX*4 + 1];
 #endif
 };