--- a/cipher/poly1305.c	
+++ a/cipher/poly1305.c	
@@ -253,7 +253,7 @@ static unsigned int poly1305_final (poly1305_context_t *ctx,
 
 #ifdef USE_MPI_32BIT
 
-#ifdef HAVE_COMPATIBLE_GCC_ARM_PLATFORM_AS
+#if defined (__arm__) && defined (HAVE_COMPATIBLE_GCC_ARM_PLATFORM_AS)
 
 /* HI:LO += A * B (arm) */
 #define UMUL_ADD_32(HI, LO, A, B) \
@@ -272,7 +272,7 @@ static unsigned int poly1305_final (poly1305_context_t *ctx,
 	       : "r" (B0), "r" (B1), "r" (B2), "r" (B3), "r" (B4) \
 	       : "cc" )
 
-#endif /* HAVE_COMPATIBLE_GCC_ARM_PLATFORM_AS */
+#endif /* defined (__arm__) && defined (HAVE_COMPATIBLE_GCC_ARM_PLATFORM_AS) */
 
 #if defined (__i386__) && __GNUC__ >= 4