diff --git a/contrib/gitian-builder/bin/gbuild b/contrib/gitian-builder/bin/gbuild
--- a/contrib/gitian-builder/bin/gbuild
+++ b/contrib/gitian-builder/bin/gbuild
@@ -104,12 +104,28 @@
     end
   end
 
+  if build_desc["repositories"]
+    info "Adding repositories to the sources list (log in var/install.log)"
+    for r in build_desc["repositories"]
+      system! "on-target -u root tee -a /etc/apt/sources.list >> var/install.log 2>&1 << EOF
+#{r["source"]}
+EOF"
+    end
+  end
+
   info "Updating apt-get repository (log in var/install.log)"
   system! "on-target -u root apt-get update >> var/install.log 2>&1"
 
   info "Installing additional packages (log in var/install.log)"
   system! "on-target -u root -e DEBIAN_FRONTEND=noninteractive apt-get --no-install-recommends -y install #{build_desc["packages"].join(" ")} >> var/install.log 2>&1"
 
+  if build_desc["repositories"]
+    for r in build_desc["repositories"]
+      info "Installing additional packages from repository #{r["distribution"]} (log in var/install.log)"
+      system! "on-target -u root -e DEBIAN_FRONTEND=noninteractive apt-get -t #{r["distribution"]} --no-install-recommends -y install #{r["packages"].join(" ")} >> var/install.log 2>&1"
+    end
+  end
+
   if build_desc["alternatives"]
     info "Set alternatives (log in var/install.log)"
     for a in build_desc["alternatives"]
diff --git a/contrib/gitian-descriptors/gitian-linux.yml b/contrib/gitian-descriptors/gitian-linux.yml
--- a/contrib/gitian-descriptors/gitian-linux.yml
+++ b/contrib/gitian-descriptors/gitian-linux.yml
@@ -17,7 +17,6 @@
 - "bsdmainutils"
 - "build-essential"
 - "ca-certificates"
-- "cmake"
 - "curl"
 - "faketime"
 - "g++-aarch64-linux-gnu"
@@ -38,6 +37,11 @@
 - "libboost-all-dev"
 - "libevent-dev"
 - "libssl-dev"
+repositories:
+- "distribution": "buster-backports"
+  "source": "deb http://deb.debian.org/debian/ buster-backports main"
+  packages:
+  - "cmake"
 remotes:
 - "url": "https://github.com/Bitcoin-ABC/bitcoin-abc.git"
   "dir": "bitcoin"
diff --git a/contrib/gitian-descriptors/gitian-osx.yml b/contrib/gitian-descriptors/gitian-osx.yml
--- a/contrib/gitian-descriptors/gitian-osx.yml
+++ b/contrib/gitian-descriptors/gitian-osx.yml
@@ -11,7 +11,6 @@
 - "automake"
 - "bsdmainutils"
 - "ca-certificates"
-- "cmake"
 - "curl"
 - "faketime"
 - "fonts-tuffy"
@@ -36,6 +35,11 @@
 - "libboost-all-dev"
 - "libevent-dev"
 - "libssl-dev"
+repositories:
+- "distribution": "buster-backports"
+  "source": "deb http://deb.debian.org/debian/ buster-backports main"
+  packages:
+  - "cmake"
 remotes:
 - "url": "https://github.com/Bitcoin-ABC/bitcoin-abc.git"
   "dir": "bitcoin"
diff --git a/contrib/gitian-descriptors/gitian-win.yml b/contrib/gitian-descriptors/gitian-win.yml
--- a/contrib/gitian-descriptors/gitian-win.yml
+++ b/contrib/gitian-descriptors/gitian-win.yml
@@ -11,7 +11,6 @@
 - "automake"
 - "bsdmainutils"
 - "ca-certificates"
-- "cmake"
 - "curl"
 - "faketime"
 - "g++"
@@ -30,6 +29,11 @@
 - "libboost-all-dev"
 - "libevent-dev"
 - "libssl-dev"
+repositories:
+- "distribution": "buster-backports"
+  "source": "deb http://deb.debian.org/debian/ buster-backports main"
+  packages:
+  - "cmake"
 remotes:
 - "url": "https://github.com/Bitcoin-ABC/bitcoin-abc.git"
   "dir": "bitcoin"