--- a/make/autoconf/build-aux/config.guess	Thu Jun 20 10:12:31 2019 -0400
+++ b/make/autoconf/build-aux/config.guess	Thu Jun 20 09:35:41 2019 -0700
@@ -63,7 +63,7 @@
 # Test and fix wsl
 echo $OUT | grep x86_64-unknown-linux-gnu > /dev/null 2> /dev/null
 if test $? = 0; then
-  uname -r | grep Microsoft > /dev/null 2> /dev/null
+  uname -r | grep -i microsoft > /dev/null 2> /dev/null
   if test $? = 0; then
     OUT="x86_64-pc-wsl"
   fi