diff --git a/packages/angular_devkit/build_angular/src/browser/schema.json b/packages/angular_devkit/build_angular/src/browser/schema.json
index fa2d8c970e70..2219b831b679 100644
--- a/packages/angular_devkit/build_angular/src/browser/schema.json
+++ b/packages/angular_devkit/build_angular/src/browser/schema.json
@@ -59,6 +59,7 @@
     "optimization": {
       "description": "Enables optimization of the build output.",
       "x-user-analytics": 16,
+      "default": false,
       "oneOf": [
         {
           "type": "object",
diff --git a/packages/angular_devkit/build_angular/src/server/schema.json b/packages/angular_devkit/build_angular/src/server/schema.json
index 6519f1a718a2..b62571479787 100644
--- a/packages/angular_devkit/build_angular/src/server/schema.json
+++ b/packages/angular_devkit/build_angular/src/server/schema.json
@@ -31,6 +31,7 @@
     "optimization": {
       "description": "Enables optimization of the build output.",
       "x-user-analytics": 16,
+      "default": false,
       "oneOf": [
         {
           "type": "object",