diff --git a/Include/pyport.h b/Include/pyport.h
index 115b54fd969287..2abeb4942501b6 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -422,32 +422,6 @@ extern "C" {
 #  define Py_NO_INLINE
 #endif
 
-/**************************************************************************
-Prototypes that are missing from the standard include files on some systems
-(and possibly only some versions of such systems.)
-
-Please be conservative with adding new ones, document them and enclose them
-in platform-specific #ifdefs.
-**************************************************************************/
-
-#ifdef SOLARIS
-/* Unchecked */
-extern int gethostname(char *, int);
-#endif
-
-#ifdef HAVE__GETPTY
-#include <sys/types.h>          /* we need to import mode_t */
-extern char * _getpty(int *, int, mode_t, int);
-#endif
-
-/* On QNX 6, struct termio must be declared by including sys/termio.h
-   if TCGETA, TCSETA, TCSETAW, or TCSETAF are used.  sys/termio.h must
-   be included before termios.h or it will generate an error. */
-#if defined(HAVE_SYS_TERMIO_H) && !defined(__hpux)
-#include <sys/termio.h>
-#endif
-
-
 /* On 4.4BSD-descendants, ctype functions serves the whole range of
  * wchar_t character set rather than single byte code points only.
  * This characteristic can break some operations of string object
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 0436571abc9054..761542866d8f96 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -58,6 +58,13 @@
 #include <stdio.h>                // ctermid()
 #include <stdlib.h>               // system()
 
+// SGI apparently needs this forward declaration
+#ifdef HAVE__GETPTY
+#  include <sys/types.h>          // mode_t
+   extern char * _getpty(int *, int, mode_t, int);
+#endif
+
+
 /*
  * A number of APIs are available on macOS from a certain macOS version.
  * To support building with a new SDK while deploying to older versions
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index e3681853dad095..2f12c9cedbd8a6 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -111,9 +111,13 @@ Local naming conventions:
 #include "pycore_fileutils.h"     // _Py_set_inheritable()
 #include "pycore_moduleobject.h"  // _PyModule_GetState
 
+// gethostname() prototype missing from Solaris standard header files
+#ifdef __sun
+extern int gethostname(char *, int);
+#endif
 
 #ifdef _Py_MEMORY_SANITIZER
-# include <sanitizer/msan_interface.h>
+#  include <sanitizer/msan_interface.h>
 #endif
 
 /* Socket object documentation */
diff --git a/Modules/termios.c b/Modules/termios.c
index 21d3541c177bc3..a0613837ef9795 100644
--- a/Modules/termios.c
+++ b/Modules/termios.c
@@ -6,10 +6,17 @@
 
 #include "Python.h"
 
-/* Apparently, on SGI, termios.h won't define CTRL if _XOPEN_SOURCE
-   is defined, so we define it here. */
+// On QNX 6, struct termio must be declared by including sys/termio.h
+// if TCGETA, TCSETA, TCSETAW, or TCSETAF are used. sys/termio.h must
+// be included before termios.h or it will generate an error.
+#if defined(HAVE_SYS_TERMIO_H) && !defined(__hpux)
+#  include <sys/termio.h>
+#endif
+
+// Apparently, on SGI, termios.h won't define CTRL if _XOPEN_SOURCE
+// is defined, so we define it here.
 #if defined(__sgi)
-#define CTRL(c) ((c)&037)
+#  define CTRL(c) ((c)&037)
 #endif
 
 #if defined(__sun)