Index: src/platform.h
==================================================================
--- src/platform.h
+++ src/platform.h
@@ -27,11 +27,11 @@
 # elif !__LITTLE_ENDIAN__
 #  error OF_UNIVERSAL defined, but neither __BIG_ENDIAN__ nor __LITTLE_ENDIAN__!
 # endif
 #endif
 
-#if defined(__x86_64__) || defined(__amd64__)
+#if (defined(__x86_64__) || defined(__amd64__)) && defined(__LP64__)
 # define OF_AMD64
 #elif defined(__i386__)
 # define OF_X86
 #elif defined(__powerpc64__) || defined(__ppc64__) || defined(__PPC64__)
 # define OF_POWERPC64