diff --git a/debian/rules b/debian/rules
index aefcf952..5aa65ffa 100755
--- a/debian/rules
+++ b/debian/rules
@@ -1,7 +1,7 @@
 #!/usr/bin/make -f
 
-DEB_PYTHON_SYSTEM=pycentral
-DEB_DH_INSTALLCHANGELOGS_ARGS=ChangeLog.txt
+DEB_PYTHON_SYSTEM:=pycentral
+DEB_DH_INSTALLCHANGELOGS_ARGS:=ChangeLog.txt
 
 # workaround for Debian bug #486848
 binary-arch binary-indep: install-arch install-indep