diff --git a/docs/user/build-default-versions.rst b/docs/user/build-default-versions.rst
index bb9a426c7a7..b6b961a45ef 100644
--- a/docs/user/build-default-versions.rst
+++ b/docs/user/build-default-versions.rst
@@ -58,7 +58,8 @@ mock:
   ``1.0.1`` (could be removed in the future).
 
 pillow:
-  ``5.4.1`` (could be removed in the future).
+  ``5.4.1`` when using Python 2.7, 3.4, 3.5, 3.6, 3.7. Otherwise, its latest version
+  (could be removed in the future).
 
 alabaster:
   ``0.7.x`` (could be removed in the future).
diff --git a/readthedocs/doc_builder/python_environments.py b/readthedocs/doc_builder/python_environments.py
index 86db7acb894..f3fa0276d0d 100644
--- a/readthedocs/doc_builder/python_environments.py
+++ b/readthedocs/doc_builder/python_environments.py
@@ -169,13 +169,23 @@ def install_core_requirements(self):
             *cmd, bin_path=self.venv_bin(), cwd=self.checkout_path
         )
 
-        requirements = [
-            'mock==1.0.1',
-            'pillow==5.4.1',
-            'alabaster>=0.7,<0.8,!=0.7.5',
-            'commonmark==0.8.1',
-            'recommonmark==0.5.0',
-        ]
+        requirements = []
+
+        # Unpin Pillow on newer Python versions to avoid re-compiling
+        # https://pillow.readthedocs.io/en/stable/installation.html#python-support
+        if self.config.python.version in ("2.7", "3.4", "3.5", "3.6", "3.7"):
+            requirements.append("pillow==5.4.1")
+        else:
+            requirements.append("pillow")
+
+        requirements.extend(
+            [
+                "mock==1.0.1",
+                "alabaster>=0.7,<0.8,!=0.7.5",
+                "commonmark==0.8.1",
+                "recommonmark==0.5.0",
+            ]
+        )
 
         if self.config.doctype == 'mkdocs':
             requirements.append(
diff --git a/readthedocs/projects/tests/test_build_tasks.py b/readthedocs/projects/tests/test_build_tasks.py
index f4222bb8396..21f8f2243ad 100644
--- a/readthedocs/projects/tests/test_build_tasks.py
+++ b/readthedocs/projects/tests/test_build_tasks.py
@@ -579,8 +579,8 @@ def test_build_commands_executed(self, load_yaml_config):
                     "install",
                     "--upgrade",
                     "--no-cache-dir",
+                    "pillow",
                     "mock==1.0.1",
-                    "pillow==5.4.1",
                     "alabaster>=0.7,<0.8,!=0.7.5",
                     "commonmark==0.8.1",
                     "recommonmark==0.5.0",
diff --git a/readthedocs/rtd_tests/tests/test_doc_building.py b/readthedocs/rtd_tests/tests/test_doc_building.py
index f1b2d570bad..6d1642780e9 100644
--- a/readthedocs/rtd_tests/tests/test_doc_building.py
+++ b/readthedocs/rtd_tests/tests/test_doc_building.py
@@ -368,9 +368,9 @@ def setUp(self):
         self.build_env_mock = Mock()
 
         self.base_requirements = [
-            'mock',
-            'pillow',
-            'alabaster',
+            "pillow",
+            "mock",
+            "alabaster",
         ]
         self.base_conda_requirements = [
             'mock',
@@ -395,7 +395,7 @@ def assertArgsStartsWith(self, args, call):
         for arg, arg_mock in zip_longest(args, args_mock):
             if arg is not mock.ANY:
                 self.assertIsNotNone(arg_mock)
-                self.assertTrue(arg_mock.startswith(arg))
+                self.assertTrue(arg_mock.startswith(arg), arg)
 
     @patch('readthedocs.projects.models.Project.checkout_path')
     def test_install_core_requirements_sphinx(self, checkout_path):