diff --git a/tests/unit/style/parsing/transition_timing_function.rs b/tests/unit/style/parsing/transition_timing_function.rs
index 898329c280f..d9f93668625 100644
--- a/tests/unit/style/parsing/transition_timing_function.rs
+++ b/tests/unit/style/parsing/transition_timing_function.rs
@@ -31,3 +31,19 @@ fn test_steps() {
     assert!(parse(transition_timing_function::parse, "steps(0.5)").is_err());
     assert!(parse(transition_timing_function::parse, "steps(-1)").is_err());
 }
+
+#[test]
+fn test_frames() {
+    assert_roundtrip_with_context!(transition_timing_function::parse, "frames(  2 )", "frames(2)");
+    assert_roundtrip_with_context!(transition_timing_function::parse, "frames(10000)");
+
+    // Frames number must be an integer greater than 1
+    assert!(parse(transition_timing_function::parse, "frames(1)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(-2)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames()").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(,)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(a)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(2.0)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(2.5)").is_err());
+    assert!(parse(transition_timing_function::parse, "frames(2 3)").is_err());
+}
diff --git a/tests/unit/style/properties/serialization.rs b/tests/unit/style/properties/serialization.rs
index fea8d3f416e..01d8e894ff6 100644
--- a/tests/unit/style/properties/serialization.rs
+++ b/tests/unit/style/properties/serialization.rs
@@ -1209,6 +1209,19 @@ mod shorthand_serialization {
 
             assert_eq!(serialization, block_text);
         }
+
+        #[test]
+        fn transition_should_serialize_acceptable_frames_timing_function() {
+            let block_text = "transition-property: margin-left; \
+                              transition-duration: 3s; \
+                              transition-delay: 4s; \
+                              transition-timing-function: frames(2);";
+            let block = parse(|c, i| Ok(parse_property_declaration_list(c, i)), block_text).unwrap();
+
+            let serialization = block.to_css_string();
+
+            assert_eq!(serialization, "transition: margin-left 3s frames(2) 4s;");
+        }
     }
 
     mod keywords {