diff --git a/taskcluster/ci/fetch/toolchains.yml b/taskcluster/ci/fetch/toolchains.yml
index 632bfd45e41a..7d64482bed16 100644
--- a/taskcluster/ci/fetch/toolchains.yml
+++ b/taskcluster/ci/fetch/toolchains.yml
@@ -291,3 +291,10 @@ tup:
         type: git
         repo: https://github.com/gittup/tup
         revision: 4371a41ba4ece660bf060b598b9eee4c2eb347d8
+
+rust-size:
+    description: rust-size source code
+    fetch:
+        type: git
+        repo: https://github.com/luser/rust-size
+        revision: ab659d93b1faba95307df952aefe3fbed3583669
diff --git a/taskcluster/ci/toolchain/rust-size.yml b/taskcluster/ci/toolchain/rust-size.yml
index e66fd58826f8..2e262eb9d0ff 100644
--- a/taskcluster/ci/toolchain/rust-size.yml
+++ b/taskcluster/ci/toolchain/rust-size.yml
@@ -10,6 +10,9 @@ job-defaults:
         script: build-rust-size.sh
         resources:
             - 'taskcluster/scripts/misc/tooltool-download.sh'
+    fetches:
+        fetch:
+            - rust-size
 
 linux64-rust-size:
     treeherder:
diff --git a/taskcluster/scripts/misc/build-rust-size.sh b/taskcluster/scripts/misc/build-rust-size.sh
index 58a05d426293..693a1bab641b 100755
--- a/taskcluster/scripts/misc/build-rust-size.sh
+++ b/taskcluster/scripts/misc/build-rust-size.sh
@@ -1,9 +1,7 @@
 #!/bin/bash
 set -x -e -v
 
-OWNER=luser
 PROJECT=rust-size
-PROJECT_REVISION=ab659d93b1faba95307df952aefe3fbed3583669
 
 # This script is for building rust-size
 case "$(uname -s)" in
@@ -36,11 +34,7 @@ fi
 
 PATH="$PWD/rustc/bin:$PATH"
 
-git clone -n https://github.com/${OWNER}/${PROJECT} ${PROJECT}
-
-cd $PROJECT
-
-git checkout $PROJECT_REVISION
+cd $MOZ_FETCHES_DIR/$PROJECT
 
 cargo build --verbose --release