diff --git a/build-clair.jenkins b/build-clair.jenkins
index 268cce1..7f52d1a 100644
--- a/build-clair.jenkins
+++ b/build-clair.jenkins
@@ -66,7 +66,9 @@ spec:
 				def dockerfile = """
 FROM quay.io/coreos/clair-jwt:v2.1.3-alpine
 COPY ${caName} /usr/local/share/ca-certificates/
-RUN update-ca-certificates --fresh
+RUN apk add --no-cache --virtual=.packagecache ca-certificates && \\
+	update-ca-certificates --fresh && \\
+	apk del .packagecache
 """
 				writeFile (file: workspace + "/${caName}", text: caContent)
 				writeFile (file: workspace + "/Dockerfile", text: dockerfile)