diff --git a/idlib/math/Simd_AltiVec.cpp b/idlib/math/Simd_AltiVec.cpp
index 96ac930..8f8ab4e 100644
--- a/idlib/math/Simd_AltiVec.cpp
+++ b/idlib/math/Simd_AltiVec.cpp
@@ -45,7 +45,7 @@ If you have questions concerning this license or the applicable additional terms
 //
 //===============================================================
 
-#if defined(__GNUC__) && defined(__ALTIVEC__)
+#if defined(MACOS_X) && defined(__GNUC__) && defined(__ALTIVEC__)
 
 #ifdef PPC_INTRINSICS
 	// for square root estimate instruction
diff --git a/idlib/math/Simd_AltiVec.h b/idlib/math/Simd_AltiVec.h
index 2a5776e..d508082 100644
--- a/idlib/math/Simd_AltiVec.h
+++ b/idlib/math/Simd_AltiVec.h
@@ -110,7 +110,7 @@ If you have questions concerning this license or the applicable additional terms
 //#define DRAWVERT_PADDED
 
 class idSIMD_AltiVec : public idSIMD_Generic {
-#if defined(__GNUC__) && defined(__ALTIVEC__)
+#if defined(MACOS_X) && defined(__GNUC__) && defined(__ALTIVEC__)
 public:
 
 	virtual const char * VPCALL GetName( void ) const;