diff --git a/dockerfile b/dockerfile
index d865a8c..c61641e 100644
--- a/dockerfile
+++ b/dockerfile
@@ -2,9 +2,10 @@ FROM sharelatex/sharelatex:6.1.2
 
 SHELL ["/bin/bash", "-cx"]
 
-# update tlmgr itself
-RUN wget "https://mirror.ctan.org/systems/texlive/tlnet/update-tlmgr-latest.sh" \
-    && sh update-tlmgr-latest.sh \
+COPY update-tlmgr-latest.sh .
+
+# update tlmgr itsel\f
+RUN sh update-tlmgr-latest.sh \
     && tlmgr --version
 
 # enable tlmgr to install ctex