diff --git a/Dockerfile b/Dockerfile
index 69168a3..5f1a3de 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,15 +1,13 @@
-FROM debian
+FROM debian:buster
 
 # Prepare image and install dependencies
 ENV LANG=C.UTF-8
 ARG DEBIAN_FRONTEND=noninteractive
 
-RUN apt-get update && apt-get upgrade -y
-
-RUN apt-get install -y flex bison build-essential \
+RUN apt-get update && apt-get install -y \
+    flex bison build-essential \
     csh libxaw7-dev wget \
-    libc6-i386 default-jdk \
-    gdb
+    libc6-i386 default-jdk
 
 RUN mkdir -p /tmp/build
 COPY . /tmp/build