diff --git a/build/tfs/darwin/continuous-build-darwin.yml b/build/tfs/darwin/continuous-build-darwin.yml
index fb753fdded1..28e2a6079ab 100644
--- a/build/tfs/darwin/continuous-build-darwin.yml
+++ b/build/tfs/darwin/continuous-build-darwin.yml
@@ -17,6 +17,9 @@ steps:
 - script: |
     yarn monaco-compile-check
   displayName: Run Monaco Editor Checks
+- script: |
+    yarn strict-null-check
+  displayName: Run Strict Null Checks
 - script: |
     yarn compile
   displayName: Compile Sources
diff --git a/build/tfs/darwin/product-build-darwin.yml b/build/tfs/darwin/product-build-darwin.yml
index 7911a60817d..f5520d06036 100644
--- a/build/tfs/darwin/product-build-darwin.yml
+++ b/build/tfs/darwin/product-build-darwin.yml
@@ -13,6 +13,7 @@ steps:
     yarn
     yarn gulp -- hygiene
     yarn monaco-compile-check
+    yarn strict-null-check
     VSCODE_MIXIN_PASSWORD="$(VSCODE_MIXIN_PASSWORD)" yarn gulp -- mixin
     node build/tfs/common/installDistro.js
     node build/lib/builtInExtensions.js
diff --git a/build/tfs/linux/continuous-build-linux.yml b/build/tfs/linux/continuous-build-linux.yml
index 1ec363a4066..459b82b9a39 100644
--- a/build/tfs/linux/continuous-build-linux.yml
+++ b/build/tfs/linux/continuous-build-linux.yml
@@ -27,6 +27,9 @@ steps:
 - script: |
     yarn monaco-compile-check
   displayName: Run Monaco Editor Checks
+- script: |
+    yarn strict-null-check
+  displayName: Run Strict Null Checks
 - script: |
     yarn compile
   displayName: Compile Sources
diff --git a/build/tfs/linux/product-build-linux.yml b/build/tfs/linux/product-build-linux.yml
index 24835a59ca6..7a8c637ef84 100644
--- a/build/tfs/linux/product-build-linux.yml
+++ b/build/tfs/linux/product-build-linux.yml
@@ -18,6 +18,7 @@ steps:
     CHILD_CONCURRENCY=1 yarn
     npm run gulp -- hygiene
     npm run monaco-compile-check
+    npm run strict-null-check
     VSCODE_MIXIN_PASSWORD="$(VSCODE_MIXIN_PASSWORD)" npm run gulp -- mixin
     node build/tfs/common/installDistro.js
     node build/lib/builtInExtensions.js
diff --git a/build/tfs/win32/continuous-build-win32.yml b/build/tfs/win32/continuous-build-win32.yml
index 83e56327fa1..0df397a0a6a 100644
--- a/build/tfs/win32/continuous-build-win32.yml
+++ b/build/tfs/win32/continuous-build-win32.yml
@@ -21,6 +21,9 @@ steps:
 - powershell: |
     yarn monaco-compile-check
   displayName: Run Monaco Editor Checks
+- script: |
+    yarn strict-null-check
+  displayName: Run Strict Null Checks
 - powershell: |
     yarn compile
   displayName: Compile Sources
diff --git a/build/tfs/win32/product-build-win32.yml b/build/tfs/win32/product-build-win32.yml
index 0baed977782..9dd2d4c6516 100644
--- a/build/tfs/win32/product-build-win32.yml
+++ b/build/tfs/win32/product-build-win32.yml
@@ -22,6 +22,7 @@ steps:
     exec { yarn }
     exec { npm run gulp -- hygiene }
     exec { npm run monaco-compile-check }
+    exec { npm run strict-null-check }
     exec { npm run gulp -- mixin }
     exec { node build/tfs/common/installDistro.js }
     exec { node build/lib/builtInExtensions.js }
diff --git a/package.json b/package.json
index 29a6a176c40..ad3585d88fc 100644
--- a/package.json
+++ b/package.json
@@ -15,14 +15,15 @@
     "watch": "gulp watch --max_old_space_size=4095",
     "watch-client": "gulp watch-client --max_old_space_size=4095",
     "monaco-editor-test": "mocha --only-monaco-editor",
-    "precommit": "node build/gulpfile.hygiene.js",
+    "precommit": "node build/gulpfile.hygiene.js && npm run strict-null-check",
     "gulp": "gulp --max_old_space_size=4095",
     "7z": "7z",
     "update-grammars": "node build/npm/update-all-grammars.js",
     "update-localization-extension": "node build/npm/update-localization-extension.js",
     "smoketest": "cd test/smoke && node test/index.js",
     "monaco-compile-check": "tsc -p src/tsconfig.monaco.json --noEmit",
-    "download-builtin-extensions": "node build/lib/builtInExtensions.js"
+    "download-builtin-extensions": "node build/lib/builtInExtensions.js",
+    "strict-null-check": "tsc -p src/tsconfig.strictNullChecks.json"
   },
   "dependencies": {
     "applicationinsights": "1.0.5",