diff --git a/.appveyor.yml b/.appveyor.yml
index ff518854864c1f..e9dd60b31f6891 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -349,7 +349,7 @@ before_build:
 build_script:
   # Build with Cargo first. Both builds produce a deno.exe in the same dir. We
   # want the final one (which gets tested and released) to be built by Ninja.
-  - cargo build -vv --release
+  - cargo build -vv --release --locked
   - ps: Set-FilesNeeded -Auto -Reason "Cargo build finished"
 
   - python tools\build.py
diff --git a/.travis.yml b/.travis.yml
index c1bdb226739065..b946708cb055d8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -106,7 +106,7 @@ jobs:
     - name: "cargo release linux"
       os: linux
       script:
-      - cargo build -vv --release
+      - cargo build -vv --release --locked
 
     # LSAN: We are in the process of getting a completely clean LSAN build,
     # but it will take some work. So for now we just run a subset of the