diff --git a/ext/pdo_sqlite/sqlite_driver.c b/ext/pdo_sqlite/sqlite_driver.c
index 7cd8880b86099..c1dcaa7fc2bca 100644
--- a/ext/pdo_sqlite/sqlite_driver.c
+++ b/ext/pdo_sqlite/sqlite_driver.c
@@ -750,7 +750,7 @@ static char *make_filename_safe(const char *filename)
 		}
 		return estrdup(filename);
 	}
-	if (*filename && memcmp(filename, ":memory:", sizeof(":memory:"))) {
+	if (*filename && strcmp(filename, ":memory:")) {
 		char *fullpath = expand_filepath(filename, NULL);
 
 		if (!fullpath) {
diff --git a/ext/pdo_sqlite/tests/gh13991.phpt b/ext/pdo_sqlite/tests/gh13991.phpt
new file mode 100644
index 0000000000000..fa847f8ba5b42
--- /dev/null
+++ b/ext/pdo_sqlite/tests/gh13991.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Fix GH-13984: Buffer size is now checked before memcmp
+--EXTENSIONS--
+pdo_sqlite
+--SKIPIF--
+<?php if (file_exists(getcwd() . '/13991db')) die('skip File "13991db" already exists.'); ?>
+--FILE--
+<?php
+$dbfile = '13991db';
+$db = new PDO('sqlite:' . $dbfile, null, null, [PDO::ATTR_PERSISTENT => true]);
+echo 'done!';
+?>
+--CLEAN--
+<?php
+@unlink(getcwd() . '/13991db');
+?>
+--EXPECT--
+done!