--- a/magick/studio.h
+++ b/magick/studio.h
@@ -51,7 +51,7 @@
   threads.  Most CPUs have cache lines of 32 or 64 bytes.  IBM Power CPUs have
   cache lines of 128 bytes.
 */
-#if defined(MAGICK_TARGET_CPU) && (MAGICK_TARGET_CPU == powerpc)
+#ifdef __powerpc__
 #  define MAGICK_CACHE_LINE_SIZE 128
 #else
 #  define MAGICK_CACHE_LINE_SIZE 64