diff --git a/CMakeLists.txt b/CMakeLists.txt
index dc6e0d2f..c32b707c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,6 +125,9 @@ elseif(MSVC)
   set(CMAKE_C_FLAGS   "-Wall -WX ${MSVC_DISABLED_WARNINGS_STR} ${MSVC_LEVEL4_WARNINGS_STR}")
   set(CMAKE_CXX_FLAGS "-Wall -WX ${MSVC_DISABLED_WARNINGS_STR} ${MSVC_LEVEL4_WARNINGS_STR}")
   set(CMAKE_ASM_NASM_FLAGS "-g cv8")
+endif()
+
+if(WIN32)
   add_definitions(-D_HAS_EXCEPTIONS=0)
   add_definitions(-DWIN32_LEAN_AND_MEAN)
   add_definitions(-DNOMINMAX)
diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index 651793fd..8541bbb7 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -47,7 +47,7 @@ if(NOT OPENSSL_NO_ASM)
       endforeach()
     endif()
   else()
-    if (CMAKE_CL_64)
+    if (${ARCH} STREQUAL "x86_64")
       set(PERLASM_STYLE nasm)
     else()
       set(PERLASM_STYLE win32n)
diff --git a/crypto/bio/printf.c b/crypto/bio/printf.c
index 3709fcb2..f59a15f6 100644
--- a/crypto/bio/printf.c
+++ b/crypto/bio/printf.c
@@ -83,7 +83,7 @@ int BIO_printf(BIO *bio, const char *format, ...) {
     va_start(args, format);
     out_len = _vscprintf(format, args);
     va_end(args);
-    assert(out_len >= sizeof(buf));
+    assert(out_len >= (int)sizeof(buf));
   }
 #endif
 
diff --git a/crypto/cpu-intel.c b/crypto/cpu-intel.c
index ef327df0..01000894 100644
--- a/crypto/cpu-intel.c
+++ b/crypto/cpu-intel.c
@@ -68,7 +68,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#if defined(OPENSSL_WINDOWS)
+#if defined(_MSC_VER)
 OPENSSL_MSVC_PRAGMA(warning(push, 3))
 #include <immintrin.h>
 #include <intrin.h>
@@ -83,7 +83,7 @@ OPENSSL_MSVC_PRAGMA(warning(pop))
  * |*out_edx|. */
 static void OPENSSL_cpuid(uint32_t *out_eax, uint32_t *out_ebx,
                           uint32_t *out_ecx, uint32_t *out_edx, uint32_t leaf) {
-#if defined(OPENSSL_WINDOWS)
+#if defined(_MSC_VER)
   int tmp[4];
   __cpuid(tmp, (int)leaf);
   *out_eax = (uint32_t)tmp[0];
@@ -114,7 +114,7 @@ static void OPENSSL_cpuid(uint32_t *out_eax, uint32_t *out_ebx,
 /* OPENSSL_xgetbv returns the value of an Intel Extended Control Register (XCR).
  * Currently only XCR0 is defined by Intel so |xcr| should always be zero. */
 static uint64_t OPENSSL_xgetbv(uint32_t xcr) {
-#if defined(OPENSSL_WINDOWS)
+#if defined(_MSC_VER)
   return (uint64_t)_xgetbv(xcr);
 #else
   uint32_t eax, edx;
diff --git a/crypto/crypto.c b/crypto/crypto.c
index 3e1765b8..f74ef66c 100644
--- a/crypto/crypto.c
+++ b/crypto/crypto.c
@@ -107,7 +107,7 @@ uint32_t OPENSSL_armcap_P = 0;
 
 #if defined(BORINGSSL_NO_STATIC_INITIALIZER)
 static CRYPTO_once_t once = CRYPTO_ONCE_INIT;
-#elif defined(OPENSSL_WINDOWS)
+#elif defined(_MSC_VER)
 #pragma section(".CRT$XCU", read)
 static void __cdecl do_library_init(void);
 __declspec(allocate(".CRT$XCU")) void(*library_init_constructor)(void) =
diff --git a/crypto/rand_extra/forkunsafe.c b/crypto/rand_extra/forkunsafe.c
index 1a3977f8..58e241fb 100644
--- a/crypto/rand_extra/forkunsafe.c
+++ b/crypto/rand_extra/forkunsafe.c
@@ -25,6 +25,7 @@ static int g_buffering_enabled = 0;
 /* g_lock protects |g_buffering_enabled|. */
 static struct CRYPTO_STATIC_MUTEX g_lock = CRYPTO_STATIC_MUTEX_INIT;
 
+#if !defined(OPENSSL_WINDOWS)
 void RAND_enable_fork_unsafe_buffering(int fd) {
   /* We no longer support setting the file-descriptor with this function. */
   if (fd != -1) {
@@ -35,6 +36,7 @@ void RAND_enable_fork_unsafe_buffering(int fd) {
   g_buffering_enabled = 1;
   CRYPTO_STATIC_MUTEX_unlock_write(&g_lock);
 }
+#endif
 
 int rand_fork_unsafe_buffering_enabled(void) {
   CRYPTO_STATIC_MUTEX_lock_read(&g_lock);