diff --git a/Include/cpython/abstract.h b/Include/cpython/abstract.h
index 9d23c8c11be577..e08b651cb0a7f1 100644
--- a/Include/cpython/abstract.h
+++ b/Include/cpython/abstract.h
@@ -67,7 +67,10 @@ PyVectorcall_Function(PyObject *callable)
 {
     PyTypeObject *tp;
     Py_ssize_t offset;
-    vectorcallfunc *ptr;
+    union {
+        char *data;
+        vectorcallfunc *ptr;
+    } vc;
 
     assert(callable != NULL);
     tp = Py_TYPE(callable);
@@ -77,8 +80,8 @@ PyVectorcall_Function(PyObject *callable)
     assert(PyCallable_Check(callable));
     offset = tp->tp_vectorcall_offset;
     assert(offset > 0);
-    ptr = (vectorcallfunc *)(((char *)callable) + offset);
-    return *ptr;
+    vc.data = (char *)callable + offset;
+    return *vc.ptr;
 }
 
 /* Call the callable object 'callable' with the "vectorcall" calling
diff --git a/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst b/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst
new file mode 100644
index 00000000000000..fe47c4ef5dd468
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-03-24-09-27-10.bpo-40052.27P2KG.rst	
@@ -0,0 +1 @@
+Fix an alignment build warning/error in function ``PyVectorcall_Function()`` publicly exposed by ``abstract.h``.
\ No newline at end of file
diff --git a/Objects/call.c b/Objects/call.c
index 08614143246091..559b408396ddcf 100644
--- a/Objects/call.c
+++ b/Objects/call.c
@@ -205,6 +205,10 @@ PyObject *
 PyVectorcall_Call(PyObject *callable, PyObject *tuple, PyObject *kwargs)
 {
     PyThreadState *tstate = _PyThreadState_GET();
+    union {
+        char *data;
+        vectorcallfunc *ptr;
+    } vc;
 
     /* get vectorcallfunc as in PyVectorcall_Function, but without
      * the Py_TPFLAGS_HAVE_VECTORCALL check */
@@ -215,7 +219,8 @@ PyVectorcall_Call(PyObject *callable, PyObject *tuple, PyObject *kwargs)
                       Py_TYPE(callable)->tp_name);
         return NULL;
     }
-    vectorcallfunc func = *(vectorcallfunc *)(((char *)callable) + offset);
+    vc.data = (char *)callable + offset;
+    vectorcallfunc func = *vc.ptr;
     if (func == NULL) {
         _PyErr_Format(tstate, PyExc_TypeError,
                       "'%.200s' object does not support vectorcall",