--- fftw-3.1/configure.ac.orig	2006-01-28 00:16:28.000000000 +0000
+++ fftw-3.1/configure.ac	2006-02-08 15:02:19.000000000 +0000
@@ -229,6 +229,8 @@
 fi
 fi
 AC_SUBST(SIMD_CFLAGS)
+# pass simd flags to preprocessor/compiler for proper intrinsics detection.
+CPPFLAGS="$CPPFLAGS $SIMD_CFLAGS"
 
 dnl Checks for header files.
 AC_HEADER_STDC