diff --git a/jni/messenger-backend b/jni/messenger-backend
index ae0301f80..bbca9c9d5 160000
--- a/jni/messenger-backend
+++ b/jni/messenger-backend
@@ -1 +1 @@
-Subproject commit ae0301f80357186970243b05391b7f0dca6eb773
+Subproject commit bbca9c9d51f14f3576f7e8b474ccab609edc0377
diff --git a/tools/update-core.sh b/tools/update-core.sh
index 54321fe3d..8fef5b4bc 100755
--- a/tools/update-core.sh
+++ b/tools/update-core.sh
@@ -1,5 +1,6 @@
 
 # this script updates the deltachat-core sub-repository from github.
+# must be executed from the repo root.
 #
 # - make sure, the deltachat-android directory is clean
 # - make sure, deltachat-core is committed successfull before calling this script
@@ -8,9 +9,6 @@
 # to simplify core-development, files in the submodule folder are replaced by 
 # symbolic links to ../deltachat-core afterwards
 
-# get to main directory
-cd ..
-
 # remove links to the files
 rm -r jni/messenger-backend/*
 rm -r jni/messenger-backend/.??*
@@ -37,5 +35,3 @@ ln --symbolic `pwd`/deltachat-core/src     deltachat-android-ii/jni/messenger-ba
 ln --symbolic `pwd`/deltachat-core/libs    deltachat-android-ii/jni/messenger-backend/libs
 cd deltachat-android-ii
 
-# back to tools directory
-cd tools