diff --git a/builder/dockerfile.centos_core.build b/builder/dockerfile.centos_core.build
index 4574075..c277e1a 100644
--- a/builder/dockerfile.centos_core.build
+++ b/builder/dockerfile.centos_core.build
@@ -3,6 +3,7 @@ FROM centos:centos7
 ENV KASMVNC_BUILD_OS centos
 ENV KASMVNC_BUILD_OS_CODENAME core
 
+RUN yum update -y ca-certificates
 RUN yum install -y build-dep xorg-server libxfont-dev sudo
 RUN yum install -y gcc cmake git libjpeg-dev libgnutls28-dev vim wget tightvncserver
 RUN yum install -y libjpeg-dev libpng-dev libtiff-dev libgif-dev libavcodec-dev openssl-devel