diff --git a/test/builtin/drawing/test_image.py b/test/builtin/drawing/test_image.py
index eb778d69c..7f2835609 100644
--- a/test/builtin/drawing/test_image.py
+++ b/test/builtin/drawing/test_image.py
@@ -9,6 +9,7 @@
 
 import pytest
 
+from mathics.builtin.base import check_requires_list
 from mathics.core.symbols import SymbolNull
 
 # Note we test with tif, jpg, and gif. Add others?
@@ -50,10 +51,10 @@
 ]
 
 
-# @pytest.mark.skipif(
-#     not check_requires_list(["skimage"]),
-#     reason="scikit-image (AKA skimage) is needed for working with Images",
-# )
+@pytest.mark.skipif(
+    not check_requires_list(["skimage"]),
+    reason="Test doesn't work in a when scikit-image is not installed",
+)
 @pytest.mark.skipif(
     os.getenv("SANDBOX", False),
     reason="Test doesn't work in a sandboxed environment with access to local files",
diff --git a/test/builtin/numbers/test_calculus.py b/test/builtin/numbers/test_calculus.py
index e928a6619..44d36a9e3 100644
--- a/test/builtin/numbers/test_calculus.py
+++ b/test/builtin/numbers/test_calculus.py
@@ -8,7 +8,7 @@
 
 
 """
-from test.helper import check_evaluation, evaluate
+from test.helper import check_evaluation
 from typing import Optional
 
 import pytest
@@ -127,7 +127,8 @@ def test_integrate(str_expr: str, str_expected: str, assert_fail_message):
             "D[{y, -x}[2], {x, y}]",
             "D[{y, -x}[2], {x, y}]",
             [
-                "Multiple derivative specifier {x, y} does not have the form {variable, n}, where n is a non-negative machine integer."
+                "Multiple derivative specifier {x, y} does not have the form {variable,"
+                " n}, where n is a non-negative machine integer."
             ],
         ),
     ],  # Issue #502