diff --git a/mypyc/lib-rt/pythonsupport.c b/mypyc/lib-rt/pythonsupport.c
index 90fb69705a00..0a99f0ae2e29 100644
--- a/mypyc/lib-rt/pythonsupport.c
+++ b/mypyc/lib-rt/pythonsupport.c
@@ -5,6 +5,109 @@
 
 #include "pythonsupport.h"
 
+/////////////////////////////////////////
+// Adapted from bltinmodule.c in Python 3.7.0
+PyObject*
+update_bases(PyObject *bases)
+{
+    Py_ssize_t i, j;
+    PyObject *base, *meth, *new_base, *result, *new_bases = NULL;
+    PyObject *stack[1] = {bases};
+    assert(PyTuple_Check(bases));
+
+    Py_ssize_t nargs = PyTuple_GET_SIZE(bases);
+    for (i = 0; i < nargs; i++) {
+        base = PyTuple_GET_ITEM(bases, i);
+        if (PyType_Check(base)) {
+            if (new_bases) {
+                /* If we already have made a replacement, then we append every normal base,
+                   otherwise just skip it. */
+                if (PyList_Append(new_bases, base) < 0) {
+                    goto error;
+                }
+            }
+            continue;
+        }
+        if (PyObject_GetOptionalAttr(base, mypyc_interned_str.__mro_entries__, &meth) < 0) {
+            goto error;
+        }
+        if (!meth) {
+            if (new_bases) {
+                if (PyList_Append(new_bases, base) < 0) {
+                    goto error;
+                }
+            }
+            continue;
+        }
+        new_base = PyObject_Vectorcall(meth, stack, 1, NULL);
+        Py_DECREF(meth);
+        if (!new_base) {
+            goto error;
+        }
+        if (!PyTuple_Check(new_base)) {
+            PyErr_SetString(PyExc_TypeError,
+                            "__mro_entries__ must return a tuple");
+            Py_DECREF(new_base);
+            goto error;
+        }
+        if (!new_bases) {
+            /* If this is a first successful replacement, create new_bases list and
+               copy previously encountered bases. */
+            if (!(new_bases = PyList_New(i))) {
+                goto error;
+            }
+            for (j = 0; j < i; j++) {
+                base = PyTuple_GET_ITEM(bases, j);
+                PyList_SET_ITEM(new_bases, j, base);
+                Py_INCREF(base);
+            }
+        }
+        j = PyList_GET_SIZE(new_bases);
+        if (PyList_SetSlice(new_bases, j, j, new_base) < 0) {
+            goto error;
+        }
+        Py_DECREF(new_base);
+    }
+    if (!new_bases) {
+        return bases;
+    }
+    result = PyList_AsTuple(new_bases);
+    Py_DECREF(new_bases);
+    return result;
+
+error:
+    Py_XDECREF(new_bases);
+    return NULL;
+}
+
+// From Python 3.7's typeobject.c
+int
+init_subclass(PyTypeObject *type, PyObject *kwds)
+{
+    PyObject *super, *func, *result;
+    PyObject *args[2] = {(PyObject *)type, (PyObject *)type};
+
+    super = PyObject_Vectorcall((PyObject *)&PySuper_Type, args, 2, NULL);
+    if (super == NULL) {
+        return -1;
+    }
+
+    func = PyObject_GetAttr(super, mypyc_interned_str.__init_subclass__);
+    Py_DECREF(super);
+    if (func == NULL) {
+        return -1;
+    }
+
+    result = _PyObject_FastCallDict(func, NULL, 0, kwds);
+    Py_DECREF(func);
+    if (result == NULL) {
+        return -1;
+    }
+
+    Py_DECREF(result);
+    return 0;
+}
+
 #if CPY_3_12_FEATURES
 
 // Slow path of CPyLong_AsSsize_tAndOverflow (non-inlined)
diff --git a/mypyc/lib-rt/pythonsupport.h b/mypyc/lib-rt/pythonsupport.h
index 1d29bdb6ab77..4c82ff6a3c03 100644
--- a/mypyc/lib-rt/pythonsupport.h
+++ b/mypyc/lib-rt/pythonsupport.h
@@ -34,108 +34,8 @@ extern "C" {
 } // why isn't emacs smart enough to not indent this
 #endif
 
-/////////////////////////////////////////
-// Adapted from bltinmodule.c in Python 3.7.0
-static PyObject*
-update_bases(PyObject *bases)
-{
-    Py_ssize_t i, j;
-    PyObject *base, *meth, *new_base, *result, *new_bases = NULL;
-    PyObject *stack[1] = {bases};
-    assert(PyTuple_Check(bases));
-
-    Py_ssize_t nargs = PyTuple_GET_SIZE(bases);
-    for (i = 0; i < nargs; i++) {
-        base = PyTuple_GET_ITEM(bases, i);
-        if (PyType_Check(base)) {
-            if (new_bases) {
-                /* If we already have made a replacement, then we append every normal base,
-                   otherwise just skip it. */
-                if (PyList_Append(new_bases, base) < 0) {
-                    goto error;
-                }
-            }
-            continue;
-        }
-        if (PyObject_GetOptionalAttrString(base, "__mro_entries__", &meth) < 0) {
-            goto error;
-        }
-        if (!meth) {
-            if (new_bases) {
-                if (PyList_Append(new_bases, base) < 0) {
-                    goto error;
-                }
-            }
-            continue;
-        }
-        new_base = PyObject_Vectorcall(meth, stack, 1, NULL);
-        Py_DECREF(meth);
-        if (!new_base) {
-            goto error;
-        }
-        if (!PyTuple_Check(new_base)) {
-            PyErr_SetString(PyExc_TypeError,
-                            "__mro_entries__ must return a tuple");
-            Py_DECREF(new_base);
-            goto error;
-        }
-        if (!new_bases) {
-            /* If this is a first successful replacement, create new_bases list and
-               copy previously encountered bases. */
-            if (!(new_bases = PyList_New(i))) {
-                goto error;
-            }
-            for (j = 0; j < i; j++) {
-                base = PyTuple_GET_ITEM(bases, j);
-                PyList_SET_ITEM(new_bases, j, base);
-                Py_INCREF(base);
-            }
-        }
-        j = PyList_GET_SIZE(new_bases);
-        if (PyList_SetSlice(new_bases, j, j, new_base) < 0) {
-            goto error;
-        }
-        Py_DECREF(new_base);
-    }
-    if (!new_bases) {
-        return bases;
-    }
-    result = PyList_AsTuple(new_bases);
-    Py_DECREF(new_bases);
-    return result;
-
-error:
-    Py_XDECREF(new_bases);
-    return NULL;
-}
-
-// From Python 3.7's typeobject.c
-static int
-init_subclass(PyTypeObject *type, PyObject *kwds)
-{
-    PyObject *super, *func, *result;
-    PyObject *args[2] = {(PyObject *)type, (PyObject *)type};
-
-    super = PyObject_Vectorcall((PyObject *)&PySuper_Type, args, 2, NULL);
-    if (super == NULL) {
-        return -1;
-    }
-
-    func = PyObject_GetAttrString(super, "__init_subclass__");
-    Py_DECREF(super);
-    if (func == NULL) {
-        return -1;
-    }
-
-    result = _PyObject_FastCallDict(func, NULL, 0, kwds);
-    Py_DECREF(func);
-    if (result == NULL) {
-        return -1;
-    }
-
-    Py_DECREF(result);
-    return 0;
-}
+PyObject* update_bases(PyObject *bases);
+int init_subclass(PyTypeObject *type, PyObject *kwds);
 
 Py_ssize_t
 CPyLong_AsSsize_tAndOverflow_(PyObject *vv, int *overflow);