diff --git a/13/Dockerfile b/13/Dockerfile
index bdf6d4f..c02b34d 100644
--- a/13/Dockerfile
+++ b/13/Dockerfile
@@ -139,7 +139,7 @@ RUN set -eux; \
 		/usr/local/share/man \
 	; \
 	\
-    apk --no-cache update; \
+    apk --no-cache update && apk --no-cache upgrade; \
 	postgres --version
 
 # make the sample config easier to munge (and "correct by default")