--- illumos-gcc-0f5ed4c/configure.orig
+++ illumos-gcc-0f5ed4c/configure
@@ -4543,7 +4543,7 @@
 fi
 if test "x$with_mpfr$with_mpfr_include$with_mpfr_lib" = x && test -d ${srcdir}/mpfr; then
   gmplibs='-L$$r/$(HOST_SUBDIR)/mpfr/.libs -L$$r/$(HOST_SUBDIR)/mpfr/_libs '"$gmplibs"
-  gmpinc='-I$$r/$(HOST_SUBDIR)/mpfr -I$$s/mpfr '"$gmpinc"
+  gmpinc='-I$$r/$(HOST_SUBDIR)/mpfr/src -I$$s/mpfr/src '"$gmpinc"
   # Do not test the mpfr version.  Assume that it is sufficient, since
   # it is in the source tree, and the library has not been built yet
   # but it would be included on the link line in the version check below