diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h
index 2aec78fc401..4329d4c87bc 100644
--- a/libgfortran/libgfortran.h
+++ b/libgfortran/libgfortran.h
@@ -104,9 +104,11 @@ typedef off_t gfc_offset;
 #endif
 
 #if defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ \
-    && defined __GLIBC_PREREQ && __GLIBC_PREREQ (2, 32)
+    && defined __GLIBC_PREREQ
+#if __GLIBC_PREREQ (2, 32)
 #define POWER_IEEE128 1
 #endif
+#endif
 
 /* These functions from <ctype.h> should only be used on values that can be
    represented as unsigned char, otherwise the behavior is undefined.