diff --git a/src/float_cast.h b/src/float_cast.h
index 97c72ad89..e33cda6f0 100644
--- a/src/float_cast.h
+++ b/src/float_cast.h
@@ -42,7 +42,7 @@
 **	the config.h file.
 */
 
-#if (defined (WIN32) || defined (_WIN32))
+#if (defined (WIN32) || defined (_WIN32)) && defined(_M_IX86)
 
    // Including math.h allows us to use the inline assembler versions without
    // producing errors in newer Visual Studio versions.