diff --git a/gallery_dl/extractor/tumblr.py b/gallery_dl/extractor/tumblr.py
index ff29c046..73455d2f 100644
--- a/gallery_dl/extractor/tumblr.py
+++ b/gallery_dl/extractor/tumblr.py
@@ -400,6 +400,9 @@ class TumblrAPI(oauth.OAuth1API):
         """Retrieve liked posts"""
         endpoint = "/v2/blog/{}/likes".format(blog)
         params = {"limit": "50", "before": self.before}
+        if self.api_key:
+            params["api_key"] = self.api_key
+
         while True:
             posts = self._call(endpoint, params)["liked_posts"]
             if not posts:
diff --git a/test/results/tumblr.py b/test/results/tumblr.py
index 67896590..4d0d6abc 100644
--- a/test/results/tumblr.py
+++ b/test/results/tumblr.py
@@ -334,6 +334,14 @@ __tests__ = (
     "#count"   : 1,
 },
 
+{
+    "#url"     : "http://mikf123.tumblr.com/likes",
+    "#category": ("", "tumblr", "likes"),
+    "#class"   : tumblr.TumblrLikesExtractor,
+    "#options" : {"api-secret": None},
+    "#count"   : 1,
+},
+
 {
     "#url"     : "https://www.tumblr.com/blog/view/mikf123/likes",
     "#category": ("", "tumblr", "likes"),