diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 17c50040..6e21a41f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,11 +1,22 @@
 name: CI
 
 on:
-- push
+  push:
+    paths:
+      - .github/workflows/ci.yml
+      - ext/**
+      - lib/**
+      - spec/**
+  pull-request:
+    paths:
+      - .github/workflows/ci.yml
+      - ext/**
+      - lib/**
+      - spec/**
 
 jobs:
-  test:
-    name: Test
+  unix-like:
+    name: Test on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
 
     strategy:
@@ -35,13 +46,74 @@ jobs:
           ruby-version: ${{ matrix.ruby_version }}
 
       - name: Setup Python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python_version }}
           architecture: ${{ matrix.python_architecture }}
 
       - name: Checkout
-        uses: actions/checkout@v1
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+
+      - name: Prepare environment
+        run: |
+          gem install bundler
+
+      - name: Install requirements
+        run: |
+          pip install --user numpy
+          bundle install
+
+      - name: Compile pycall.so
+        run: |
+          bundle exec rake compile
+
+      - name: Python investigator
+        run: |
+          python lib/pycall/python/investigator.py
+
+      - name: Test
+        run: |
+          PYTHON=python bundle exec rake
+
+  windows:
+    name: Test on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+        - windows-latest
+        ruby_version:
+        - 2.7.x
+        - 2.6.x
+        - 2.5.x
+        - 2.4.x
+        python_version:
+        - 3.8.x
+        - 3.7.x
+        - 3.6.x
+        - 2.7.x
+        python_architecture:
+        - x64
+
+    steps:
+      - name: Setup Ruby
+        if: matrix.ruby_version != 'master-nightly'
+        uses: actions/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby_version }}
+
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python_version }}
+          architecture: ${{ matrix.python_architecture }}
+
+      - name: Checkout
+        uses: actions/checkout@v2
         with:
           fetch-depth: 1
 
diff --git a/ext/pycall/pycall_internal.h b/ext/pycall/pycall_internal.h
index 8e734e60..a75e71a0 100644
--- a/ext/pycall/pycall_internal.h
+++ b/ext/pycall/pycall_internal.h
@@ -663,6 +663,19 @@ Py_ssize_t pycall_python_hexversion(void);
 
 void pycall_Py_DecRef(PyObject *);
 
+#if defined(_MSC_VER) && defined(RUBY_TYPED_FREE_IMMEDIATELY)
+# define PYCALL_PYPTR_PARENT 0
+# define PYCALL_PYPTR_DATA_INIT_PARENT(pyptr_data) ((pyptr_data).parent = &pycall_pyptr_data_type)
+#endif
+
+#ifndef PYCALL_PYPTR_PARENT
+# define PYCALL_PYPTR_PARENT &pycall_pyptr_data_type
+#endif
+
+#ifndef PYCALL_PYPTR_DATA_INIT_PARENT
+# define PYCALL_PYPTR_DATA_INIT_PARENT(pyptr_data) ((void)0)
+#endif
+
 RUBY_EXTERN const rb_data_type_t pycall_pyptr_data_type;
 size_t pycall_pyptr_memsize(void const *);
 void pycall_pyptr_free(void *);
diff --git a/ext/pycall/ruby_wrapper.c b/ext/pycall/ruby_wrapper.c
index a1f745b6..e08272c9 100644
--- a/ext/pycall/ruby_wrapper.c
+++ b/ext/pycall/ruby_wrapper.c
@@ -356,11 +356,17 @@ PyRuby_getattro_with_gvl(PyRubyObject *pyro, PyObject *pyobj_name)
 
 VALUE cPyRubyPtr;
 
-const rb_data_type_t pycall_pyrubyptr_data_type = {
+static rb_data_type_t pycall_pyrubyptr_data_type = {
   "PyCall::PyRubyPtr",
-  { 0, pycall_pyptr_free, pycall_pyptr_memsize, },
+  {
+    0,
+    pycall_pyptr_free,
+    pycall_pyptr_memsize,
+  },
 #ifdef RUBY_TYPED_FREE_IMMEDIATELY
-  &pycall_pyptr_data_type, 0, RUBY_TYPED_FREE_IMMEDIATELY
+  PYCALL_PYPTR_PARENT,
+  0,
+  RUBY_TYPED_FREE_IMMEDIATELY
 #endif
 };
 
@@ -462,6 +468,9 @@ pycall_init_ruby_wrapper(void)
 
   /* PyCall::PyRubyPtr */
 
+// This cannot be defined above because MSVC 2019 results in error C2099: initializer is not a constant
+  PYCALL_PYPTR_DATA_INIT_PARENT(pycall_pyrubyptr_data_type);
+
   cPyRubyPtr = rb_define_class_under(mPyCall, "PyRubyPtr", cPyPtr);
   rb_define_alloc_func(cPyRubyPtr, pycall_pyruby_allocate);
   rb_define_method(cPyRubyPtr, "__ruby_object_id__", pycall_pyruby_get_ruby_object_id, 0);