diff --git a/tools/linux/arm64/Dockerfile b/tools/linux/arm64/Dockerfile
index f1dbedc..8694068 100644
--- a/tools/linux/arm64/Dockerfile
+++ b/tools/linux/arm64/Dockerfile
@@ -1,10 +1,8 @@
 FROM arm64v8/ubuntu:16.04
 
-ARG CORES=4
-
 # basic dependencies
 RUN apt-get -y update && \
-    apt-get -y install python wget xz-utils
+    apt-get -y install wget xz-utils
 
 # qt source
 RUN mkdir /source && cd /source && \
@@ -31,6 +29,9 @@ RUN apt-get -y install \
     libxrender-dev \
     libxss-dev
 
+# increase or decrease CORES value to change the number of parallel jobs while building qt
+ENV CORES=4
+
 CMD cd /source/qt-everywhere-opensource-src-5.9.9 && \
     ./configure -opensource -confirm-license -release -shared -accessibility -prefix /build -qt-zlib -qt-libpng -qt-libjpeg -qt-xcb -qt-pcre -no-sql-sqlite -no-qml-debug -gstreamer 1.0 -nomake examples -nomake tests -skip qtenginio -skip qtlocation -skip qtserialport -skip qtsensors -skip qtxmlpatterns -skip qt3d -skip qtwebview -skip qtwebengine && \
     make -j$CORES && \