use https links where possible
diff --git a/README.txt b/README.txt
index b743b64..8a266a7 100644
--- a/README.txt
+++ b/README.txt
@@ -4,7 +4,7 @@
 Commons Compress is a Java library for working with various
 compression and archiving formats.
 
-For full documentation see http://commons.apache.org/proper/commons-compress/
+For full documentation see https://commons.apache.org/proper/commons-compress/
 
 ## Apache Commons Compress was derived from various sources, including: