diff --git a/external/fdlibm/math.h b/external/fdlibm/math.h
index 2e9e3de..4f93878 100644
--- a/external/fdlibm/math.h
+++ b/external/fdlibm/math.h
@@ -17,8 +17,10 @@
    but these catch some common cases. */
 
 #if defined(__WATCOMC__) || defined(_MSC_VER) || defined(i386) || defined(i486) || defined(intel) || defined(x86) || defined(i86pc) || defined(__alpha) || defined(__osf__) || __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#ifndef __LITTLE_ENDIAN
 #define __LITTLE_ENDIAN
 #endif
+#endif
 
 #ifdef __LITTLE_ENDIAN
 #define __HI(x) *(1 + (int*)&x)