diff --git a/src/libImaging/ImPlatform.h b/src/libImaging/ImPlatform.h
index 90d87e445..e7feff9b5 100644
--- a/src/libImaging/ImPlatform.h
+++ b/src/libImaging/ImPlatform.h
@@ -9,6 +9,11 @@
 
 #include "Python.h"
 
+/* Microsoft compiler doesn't limit intrinsics for an architecture.
+   This macro is set only on x86 and means SSE2 and above including AVX2. */
+#if defined(_M_X64) || _M_IX86_FP == 2
+    #define __SSE4_2__
+#endif
 #if defined(__SSE4_2__)
     #include <emmintrin.h>
     #include <mmintrin.h>
diff --git a/src/libImaging/ImagingUtils.h b/src/libImaging/ImagingUtils.h
index 8357719b5..ba6210886 100644
--- a/src/libImaging/ImagingUtils.h
+++ b/src/libImaging/ImagingUtils.h
@@ -52,6 +52,6 @@ mm_cvtepu8_epi32(void *ptr) {
 #if defined(__AVX2__)
 static __m256i inline
 mm256_cvtepu8_epi32(void *ptr) {
-    return _mm256_cvtepu8_epi32(_mm_cvtsi64_si128(*(int64_t *) ptr));
+    return _mm256_cvtepu8_epi32(_mm_loadl_epi64((__m128i *) ptr));
 }
 #endif