diff --git a/src/configure.ac b/src/configure.ac
index 1706a8d9a..cba718b79 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -67,8 +67,8 @@ dnl clang-500.2.75 or around has abandoned -f[no-]strength-reduce and issues a
 dnl warning when that flag is passed to.  Accordingly, adjust CFLAGS based on
 dnl the version number of the clang in use.
 dnl Note that this does not work to get the version of clang 3.1 or 3.2.
-AC_MSG_CHECKING(for recent clang version)
-CLANG_VERSION_STRING=`$CC --version 2>/dev/null | sed  -n -e 's/^.*clang.*\([[0-9]][[0-9]]*\.[[0-9]][[0-9]]*\.[[0-9]][[0-9]]*\).*$/\1/p'`
+AC_MSG_CHECKING(for clang version)
+CLANG_VERSION_STRING=`$CC --version 2>/dev/null | sed  -n -e 's/^.*clang[[^0-9]]*\([[0-9]][[0-9]]*\.[[0-9]][[0-9]]*\.[[0-9]][[0-9]]*\).*$/\1/p'`
 if test x"$CLANG_VERSION_STRING" != x"" ; then
   CLANG_MAJOR=`echo "$CLANG_VERSION_STRING" | sed -n -e 's/\([[0-9]][[0-9]]*\)\.[[0-9]][[0-9]]*\.[[0-9]][[0-9]]*/\1/p'`
   CLANG_MINOR=`echo "$CLANG_VERSION_STRING" | sed -n -e 's/[[0-9]][[0-9]]*\.\([[0-9]][[0-9]]*\)\.[[0-9]][[0-9]]*/\1/p'`
@@ -79,11 +79,15 @@ if test x"$CLANG_VERSION_STRING" != x"" ; then
   dnl change the constant 500002075 below appropriately.  To get the
   dnl integer corresponding to a version number, refer to the
   dnl definition of CLANG_VERSION above.
+  AC_MSG_CHECKING(if clang supports -fno-strength-reduce)
   if test "$CLANG_VERSION" -ge 500002075 ; then
-    CFLAGS=`echo "$CFLAGS" | sed -n -e 's/-fno-strength-reduce/ /p'`
+    AC_MSG_RESULT(no)
+    CFLAGS=`echo "$CFLAGS" | sed -e 's/-fno-strength-reduce/ /'`
+  else
+    AC_MSG_RESULT(yes)
   fi
 else
-  AC_MSG_RESULT(no)
+  AC_MSG_RESULT(N/A)
 fi
 
 dnl If configure thinks we are cross compiling, there might be something