diff --git a/rcl/src/rcl/common.c b/rcl/src/rcl/common.c
index 6838916..ca96599 100644
--- a/rcl/src/rcl/common.c
+++ b/rcl/src/rcl/common.c
@@ -23,10 +23,10 @@ extern "C"
 
 #include "rcl/allocator.h"
 
-#if defined(WIN32)
+#if defined(_WIN32)
 # define WINDOWS_ENV_BUFFER_SIZE 2048
 static char __env_buffer[WINDOWS_ENV_BUFFER_SIZE];
-#endif  // defined(WIN32)
+#endif  // defined(_WIN32)
 
 rcl_ret_t
 rcl_impl_getenv(const char * env_name, const char ** env_value)
@@ -34,12 +34,12 @@ rcl_impl_getenv(const char * env_name, const char ** env_value)
   RCL_CHECK_ARGUMENT_FOR_NULL(env_name, RCL_RET_INVALID_ARGUMENT, rcl_get_default_allocator());
   RCL_CHECK_ARGUMENT_FOR_NULL(env_value, RCL_RET_INVALID_ARGUMENT, rcl_get_default_allocator());
   *env_value = NULL;
-#if !defined(WIN32)
+#if !defined(_WIN32)
   *env_value = getenv(env_name);
   if (*env_value == NULL) {
     *env_value = "";
   }
-#else  // !defined(WIN32)
+#else  // !defined(_WIN32)
   size_t required_size;
   errno_t ret = getenv_s(&required_size, __env_buffer, sizeof(__env_buffer), env_name);
   if (ret != 0) {
@@ -48,7 +48,7 @@ rcl_impl_getenv(const char * env_name, const char ** env_value)
   }
   __env_buffer[WINDOWS_ENV_BUFFER_SIZE - 1] = '\0';
   *env_value = __env_buffer;
-#endif  // !defined(WIN32)
+#endif  // !defined(_WIN32)
   return RCL_RET_OK;
 }
 
diff --git a/rcl/src/rcl/stdatomic_helper.h b/rcl/src/rcl/stdatomic_helper.h
index 88c4140..88a7f7f 100644
--- a/rcl/src/rcl/stdatomic_helper.h
+++ b/rcl/src/rcl/stdatomic_helper.h
@@ -15,7 +15,7 @@
 #ifndef RCL__STDATOMIC_HELPER_H_
 #define RCL__STDATOMIC_HELPER_H_
 
-#if !defined(WIN32)
+#if !defined(_WIN32)
 
 #if defined(__GNUC__) && __GNUC__ <= 4 && __GNUC_MINOR__ <= 9
 // If GCC and below GCC-4.9, use the compatability header.
@@ -38,7 +38,7 @@
 
 #define rcl_atomic_store(object, desired) atomic_store(object, desired)
 
-#else  // !defined(WIN32)
+#else  // !defined(_WIN32)
 
 #include "./stdatomic_helper/win32/stdatomic.h"
 
@@ -51,7 +51,7 @@
 
 #define rcl_atomic_store(object, desired) rcl_win32_atomic_store(object, desired)
 
-#endif  // !defined(WIN32)
+#endif  // !defined(_WIN32)
 
 static inline bool
 rcl_atomic_load_bool(atomic_bool * a_bool)
diff --git a/rcl/src/rcl/stdatomic_helper/win32/stdatomic.h b/rcl/src/rcl/stdatomic_helper/win32/stdatomic.h
index 79e2fbf..77c26bb 100644
--- a/rcl/src/rcl/stdatomic_helper/win32/stdatomic.h
+++ b/rcl/src/rcl/stdatomic_helper/win32/stdatomic.h
@@ -56,9 +56,9 @@
  * $FreeBSD: src/include/stdatomic.h,v 1.10.2.2 2012/05/30 19:21:54 theraven Exp $
  */
 
-#if !defined(WIN32)
+#if !defined(_WIN32)
 #error "this stdatomic.h does not support your compiler"
-#endif
+#endif  // !defined(_WIN32)
 
 #ifndef RCL__STDATOMIC_HELPER__WIN32__STDATOMIC_H_
 #define RCL__STDATOMIC_HELPER__WIN32__STDATOMIC_H_
diff --git a/rcl/test/memory_tools/memory_tools.cpp b/rcl/test/memory_tools/memory_tools.cpp
index 37c7b82..5468d38 100644
--- a/rcl/test/memory_tools/memory_tools.cpp
+++ b/rcl/test/memory_tools/memory_tools.cpp
@@ -94,7 +94,7 @@ void stop_memory_checking()
 /******************************************************************************
  * End Apple
  *****************************************************************************/
-// #elif defined(WIN32)
+// #elif defined(_WIN32)
 /******************************************************************************
  * Begin Windows
  *****************************************************************************/
@@ -140,4 +140,4 @@ void set_on_unexpected_free_callback(UnexpectedCallbackType callback) {}
 
 void memory_checking_thread_init() {}
 
-#endif  // if defined(__linux__) elif defined(__APPLE__) elif defined(WIN32) else ...
+#endif  // if defined(__linux__) elif defined(__APPLE__) elif defined(_WIN32) else ...
diff --git a/rcl/test/rcl/test_node.cpp b/rcl/test/rcl/test_node.cpp
index 7d17eb6..c6a2e6d 100644
--- a/rcl/test/rcl/test_node.cpp
+++ b/rcl/test/rcl/test_node.cpp
@@ -56,11 +56,11 @@ public:
 
 bool is_opensplice =
   std::string(rmw_get_implementation_identifier()).find("opensplice") != std::string::npos;
-#if defined(WIN32)
+#if defined(_WIN32)
 bool is_windows = true;
 #else
 bool is_windows = false;
-#endif
+#endif  // defined(_WIN32)
 
 /* Tests the node accessors, i.e. rcl_node_get_* functions.
  */