diff --git a/configure.ac b/configure.ac
index 316114c..27ac7e3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -25,7 +25,8 @@ m4_define(x_least, m4_esyscmd_s(
   LEAST="ERROR-UNDEFINED-REVISION-to-be-built-in-subdirectory-of-svn-checkout"
   for path in . .. ../..; do
     if svn info $path 2>&1 > /dev/null; then
-      LEAST=$(LANG= svn info $path | sed -n 's/Last Changed Rev: //p')
+      # Mac does not support LEAST > 255
+      LEAST=$(($(LANG= svn info $path | sed -n 's/Last Changed Rev: //p')%256))
       (cd $path && svn2cl)
       break;
     fi