diff --git a/src/configure b/src/configure
index 15cfa8d9b16..c67d0fcbee0 100755
--- a/src/configure
+++ b/src/configure
@@ -701,7 +701,7 @@ else
   
 
 # lowercase $host
-host="`echo $host | tr 'A-Z' 'a-z'`"
+host="`echo $host | tr '[A-Z]' '[a-z]'`"
 
 # First, try for a template exactly matching $host
 if test -f "template/$host"
@@ -729,7 +729,7 @@ else
 	then TEMPLATE="$GUESS"
 	else
 	    # Last chance ... maybe uname -s will match an entry.
-	    TEMPLATE=`uname -s | tr A-Z a-z` 
+	    TEMPLATE=`uname -s | tr '[A-Z]' '[a-z]'` 
 	fi
     fi
 fi