Minor fix of conversion to lowercase.

diff --git a/Makefile.rules b/Makefile.rules
index 082344041211ee544e3e7c508742077e4edce61c..e9f8de07cac0d71da66c4728ccdc62273a9a40ab 100644 (file)
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -117,7 +117,7 @@ ifeq ($(TARGET_OS),)
   ifeq ($(OS),Windows_NT)
     TARGET_OS = win32
   else
-    TARGET_OS = $(shell uname | tr [:upper:] [:lower:] )
+    TARGET_OS = $(shell uname | tr '[A-Z]' '[a-z]' )
     #$(warning TARGET_OS=$(TARGET_OS))
   endif
 endif