diff --git a/Modules/_ctypes/libffi/src/dlmalloc.c b/Modules/_ctypes/libffi/src/dlmalloc.c
index 783c5c2..b253491 100644
--- a/Modules/_ctypes/libffi/src/dlmalloc.c
+++ b/Modules/_ctypes/libffi/src/dlmalloc.c
@@ -512,11 +512,11 @@ DEFAULT_MMAP_THRESHOLD       default: 256K
 #define MMAP_CLEARS 1
 #endif  /* MMAP_CLEARS */
 #ifndef HAVE_MREMAP
-#ifdef linux
+#ifdef __linux
 #define HAVE_MREMAP 1
-#else   /* linux */
+#else   /* __linux */
 #define HAVE_MREMAP 0
-#endif  /* linux */
+#endif  /* __linux */
 #endif  /* HAVE_MREMAP */
 #ifndef MALLOC_FAILURE_ACTION
 #define MALLOC_FAILURE_ACTION  errno = ENOMEM;
diff --git a/Modules/_ctypes/libffi/src/mips/ffitarget.h b/Modules/_ctypes/libffi/src/mips/ffitarget.h
index c5f4e05..440604d 100644
--- a/Modules/_ctypes/libffi/src/mips/ffitarget.h
+++ b/Modules/_ctypes/libffi/src/mips/ffitarget.h
@@ -27,7 +27,7 @@
 #ifndef LIBFFI_TARGET_H
 #define LIBFFI_TARGET_H
 
-#ifdef linux
+#ifdef __linux
 # include <asm/sgidefs.h>
 #else
 # include <sgidefs.h>
diff --git a/Modules/_ctypes/libffi/src/x86/ffi.c b/Modules/_ctypes/libffi/src/x86/ffi.c
index 8049653..01f7e84 100644
--- a/Modules/_ctypes/libffi/src/x86/ffi.c
+++ b/Modules/_ctypes/libffi/src/x86/ffi.c
@@ -209,7 +209,7 @@ ffi_status ffi_prep_cif_machdep(ffi_cif *cif)
 #endif
         {
           cif->flags = FFI_TYPE_STRUCT;
-          // allocate space for return value pointer
+          /* allocate space for return value pointer */
           cif->bytes += ALIGN(sizeof(void*), FFI_SIZEOF_ARG);
         }
       break;
diff --git a/Modules/fpectlmodule.c b/Modules/fpectlmodule.c
index 6af2f82..ccaa519 100644
--- a/Modules/fpectlmodule.c
+++ b/Modules/fpectlmodule.c
@@ -175,7 +175,7 @@ static void fpe_reset(Sigfunc *handler)
     PyOS_setsig(SIGFPE, handler);
 
 /*-- DEC ALPHA LINUX ------------------------------------------------------*/
-#elif defined(__alpha) && defined(linux)
+#elif defined(__alpha) && defined(__linux)
 #include <asm/fpu.h>
     unsigned long fp_control =
     IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF;
@@ -214,7 +214,7 @@ static void fpe_reset(Sigfunc *handler)
     PyOS_setsig(SIGFPE, handler);
 
 /*-- Linux ----------------------------------------------------------------*/
-#elif defined(linux)
+#elif defined(__linux)
 #ifdef __GLIBC__
 #include <fpu_control.h>
 #else
diff --git a/Modules/ossaudiodev.c b/Modules/ossaudiodev.c
index e660e50..1899db8 100644
--- a/Modules/ossaudiodev.c
+++ b/Modules/ossaudiodev.c
@@ -32,7 +32,7 @@
 #include <sys/ioctl.h>
 #include <sys/soundcard.h>
 
-#if defined(linux)
+#if defined(__linux)
 
 #ifndef HAVE_STDINT_H
 typedef unsigned long uint32_t;
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 396243e..e0083fc 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6437,7 +6437,7 @@ done:
     if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iiOn:sendfile",
             keywords, &out, &in, &offobj, &count))
         return NULL;
-#ifdef linux
+#ifdef __linux
     if (offobj == Py_None) {
         Py_BEGIN_ALLOW_THREADS
         ret = sendfile(out, in, NULL, count);
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index d3f65aa..b0c0aaa 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -150,7 +150,7 @@ if_indextoname(index) -- returns the corresponding interface name\n\
    On the other hand, not all Linux versions agree, so there the settings
    computed by the configure script are needed! */
 
-#ifndef linux
+#ifndef __linux
 # undef HAVE_GETHOSTBYNAME_R_3_ARG
 # undef HAVE_GETHOSTBYNAME_R_5_ARG
 # undef HAVE_GETHOSTBYNAME_R_6_ARG
@@ -165,7 +165,7 @@ if_indextoname(index) -- returns the corresponding interface name\n\
 #  define HAVE_GETHOSTBYNAME_R_3_ARG
 # elif defined(__sun) || defined(__sgi)
 #  define HAVE_GETHOSTBYNAME_R_5_ARG
-# elif defined(linux)
+# elif defined(__linux)
 /* Rely on the configure script */
 # else
 #  undef HAVE_GETHOSTBYNAME_R
@@ -1053,13 +1053,13 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
     case AF_UNIX:
     {
         struct sockaddr_un *a = (struct sockaddr_un *) addr;
-#ifdef linux
+#ifdef __linux
         if (a->sun_path[0] == 0) {  /* Linux abstract namespace */
             addrlen -= offsetof(struct sockaddr_un, sun_path);
             return PyBytes_FromStringAndSize(a->sun_path, addrlen);
         }
         else
-#endif /* linux */
+#endif /* __linux */
         {
             /* regular NULL-terminated string */
             return PyUnicode_FromString(a->sun_path);
@@ -1243,7 +1243,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             return 0;
 
         addr = (struct sockaddr_un*)addr_ret;
-#ifdef linux
+#ifdef __linux
         if (len > 0 && path[0] == 0) {
             /* Linux abstract namespace extension */
             if (len > sizeof addr->sun_path) {
@@ -1253,7 +1253,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             }
         }
         else
-#endif /* linux */
+#endif /* __linux */
         {
             /* regular NULL-terminated string */
             if (len >= sizeof addr->sun_path) {