diff --git a/integration/ngcc/test.sh b/integration/ngcc/test.sh
index 4c5fb4bb61..d4729a2dc3 100755
--- a/integration/ngcc/test.sh
+++ b/integration/ngcc/test.sh
@@ -42,10 +42,12 @@ function assertNotEquals {
   fi
 }
 
-
 ngcc --help
 assertSucceeded "Expected 'ngcc --help' to succeed."
 
+ngcc --unknown-option 2>&1 | grep 'Unknown arguments: unknown-option, unknownOption'
+assertSucceeded "Expected ngcc to report bad option."
+
 # node --inspect-brk $(npm bin)/ngcc -f esm2015
 # Run ngcc and check it logged compilation output as expected
 ngcc | grep 'Compiling'
diff --git a/packages/compiler-cli/ngcc/main-ngcc.ts b/packages/compiler-cli/ngcc/main-ngcc.ts
index e3a7f7d2d7..bc385c8253 100644
--- a/packages/compiler-cli/ngcc/main-ngcc.ts
+++ b/packages/compiler-cli/ngcc/main-ngcc.ts
@@ -76,6 +76,7 @@ if (require.main === module) {
             describe: 'The lowest severity logging message that should be output.',
             choices: ['debug', 'info', 'warn', 'error'],
           })
+          .strict()
           .help()
           .parse(args);