diff --git a/Modules/_ctypes/libffi/src/dlmalloc.c b/Modules/_ctypes/libffi/src/dlmalloc.c
index 6e474b7c4f0..55c2d768b29 100644
--- a/Modules/_ctypes/libffi/src/dlmalloc.c
+++ b/Modules/_ctypes/libffi/src/dlmalloc.c
@@ -525,7 +525,7 @@ 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 */
 #define HAVE_MREMAP 0
diff --git a/Modules/ossaudiodev.c b/Modules/ossaudiodev.c
index 2b7d71f64f1..4796203e57c 100644
--- a/Modules/ossaudiodev.c
+++ b/Modules/ossaudiodev.c
@@ -37,7 +37,7 @@
 #include <sys/soundcard.h>
 #endif
 
-#if defined(linux)
+#ifdef __linux__
 
 #ifndef HAVE_STDINT_H
 typedef unsigned long uint32_t;
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 0b9b3f617f2..161704fcae4 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -8446,7 +8446,7 @@ done:
     if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iiOn:sendfile",
             keywords, &out, &in, &offobj, &count))
         return NULL;
-#ifdef linux
+#ifdef __linux__
     if (offobj == Py_None) {
         do {
             Py_BEGIN_ALLOW_THREADS