diff --git a/include/SDL_config.h.cmake b/include/SDL_config.h.cmake
index a4278f16f..b87acc761 100644
--- a/include/SDL_config.h.cmake
+++ b/include/SDL_config.h.cmake
@@ -38,7 +38,7 @@
 
 /* C datatypes */
 /* Define SIZEOF_VOIDP for 64/32 architectures */
-#ifdef __LP64__
+#if defined(__LP64__) || defined(_LP64) || defined(_WIN64)
 #define SIZEOF_VOIDP 8
 #else
 #define SIZEOF_VOIDP 4
diff --git a/include/SDL_config.h.in b/include/SDL_config.h.in
index 4d53c4fac..9f09c0448 100644
--- a/include/SDL_config.h.in
+++ b/include/SDL_config.h.in
@@ -42,11 +42,12 @@
 #undef volatile
 
 /* C datatypes */
-#ifdef __LP64__
+#if defined(__LP64__) || defined(_LP64) || defined(_WIN64)
 #define SIZEOF_VOIDP 8
 #else
 #define SIZEOF_VOIDP 4
 #endif
+
 #undef HAVE_GCC_ATOMICS
 #undef HAVE_GCC_SYNC_LOCK_TEST_AND_SET