diff --git a/sha1/src/x86.S b/sha1/src/x86.S
index c7268e5..bda8be3 100644
--- a/sha1/src/x86.S
+++ b/sha1/src/x86.S
@@ -23,7 +23,7 @@
 
 
 /* void sha1_compress(uint32_t state[5], const uint8_t block[64]) */
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
 .globl _sha1_compress
 _sha1_compress:
 #else