Test deb installation - corrections
diff --git a/tests/dockerfiles/Ubuntu_16_04_debinstall.docker b/tests/dockerfiles/Ubuntu_16_04_debinstall.docker
index 0ca3321..0a476ce 100644
--- a/tests/dockerfiles/Ubuntu_16_04_debinstall.docker
+++ b/tests/dockerfiles/Ubuntu_16_04_debinstall.docker
@@ -1,7 +1,11 @@
 FROM ubuntu:16.04
 MAINTAINER Ash Wilson
 
+RUN apt-get update && apt-get install -y \
+    software-properties-common
+
 RUN add-apt-repository -y ppa:ptrkrysik/gr-gsm
+
 RUN apt-get update && apt-get install -y \
     gr-gsm