diff --git a/autogen/configure b/autogen/configure
index 9634fe55ec1..47c21af749d 100755
--- a/autogen/configure
+++ b/autogen/configure
@@ -7157,6 +7157,12 @@ fi
   nw="$nw -Wsuggest-attribute=const"
   nw="$nw -Wsuggest-attribute=pure"
 
+  # Some loops can't be optimized with -O1,
+  # so remove -Wunsafe-loop-optimizations.
+  if echo "$CFLAGS" | $EGREP 'O1' 1>/dev/null; then
+    nw="$nw -Wunsafe-loop-optimizations"
+  fi
+
 
 
   if test -n "$GCC"; then