diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 488276a..80f9164 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -4,7 +4,7 @@
 
 #include "Python.h"
 #include "Python-ast.h"
-#include "structmember.h"
+#include "structmember.h"         // PyMemberDef
 
 typedef struct {
     int initialized;
diff --git a/Python/ceval.c b/Python/ceval.c
index 5e54356..59765d8 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -29,7 +29,6 @@
 #include "opcode.h"
 #include "pydtrace.h"
 #include "setobject.h"
-#include "structmember.h"
 
 #include <ctype.h>
 
diff --git a/Python/context.c b/Python/context.c
index 15749e9..f0217f2 100644
--- a/Python/context.c
+++ b/Python/context.c
@@ -6,7 +6,7 @@
 #include "pycore_object.h"
 #include "pycore_pyerrors.h"
 #include "pycore_pystate.h"       // _PyThreadState_GET()
-#include "structmember.h"
+#include "structmember.h"         // PyMemberDef
 
 
 #define CONTEXT_FREELIST_MAXLEN 255
diff --git a/Python/hamt.c b/Python/hamt.c
index 9924e33..8801c5e 100644
--- a/Python/hamt.c
+++ b/Python/hamt.c
@@ -1,8 +1,8 @@
 #include "Python.h"
 
 #include "pycore_hamt.h"
-#include "pycore_object.h"   // _PyObject_GC_TRACK()
-#include "structmember.h"
+#include "pycore_object.h"        // _PyObject_GC_TRACK()
+#include <stddef.h>               // offsetof()
 
 /*
 This file provides an implementation of an immutable mapping using the
diff --git a/Python/structmember.c b/Python/structmember.c
index e653d02..ba88e15 100644
--- a/Python/structmember.c
+++ b/Python/structmember.c
@@ -2,8 +2,7 @@
 /* Map C struct members to Python object attributes */
 
 #include "Python.h"
-
-#include "structmember.h"
+#include "structmember.h"         // PyMemberDef
 
 PyObject *
 PyMember_GetOne(const char *addr, PyMemberDef *l)
diff --git a/Python/symtable.c b/Python/symtable.c
index a3c5d65..d192f31 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -2,7 +2,7 @@
 #include "pycore_pystate.h"   // _PyThreadState_GET()
 #include "symtable.h"
 #undef Yield   /* undefine macro conflicting with <winbase.h> */
-#include "structmember.h"
+#include "structmember.h"         // PyMemberDef
 
 /* error strings used for warnings */
 #define GLOBAL_PARAM \
diff --git a/Python/traceback.c b/Python/traceback.c
index 610c217..e3397ec 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -5,7 +5,7 @@
 
 #include "code.h"
 #include "frameobject.h"
-#include "structmember.h"
+#include "structmember.h"         // PyMemberDef
 #include "osdefs.h"
 #ifdef HAVE_FCNTL_H
 #include <fcntl.h>