diff --git a/packages/compiler/src/aot/static_reflector.ts b/packages/compiler/src/aot/static_reflector.ts
index fbd0ed5292..a3310f10e9 100644
--- a/packages/compiler/src/aot/static_reflector.ts
+++ b/packages/compiler/src/aot/static_reflector.ts
@@ -191,7 +191,6 @@ export class StaticReflector implements CompileReflector {
             if (paramType) nestedResult.push(paramType);
             const decorators = parameterDecorators ? parameterDecorators[index] : null;
             if (decorators) {
-              if (paramType) nestedResult.push(paramType);
               nestedResult.push(...decorators);
             }
             parameters !.push(nestedResult);
diff --git a/tools/@angular/tsc-wrapped/src/evaluator.ts b/tools/@angular/tsc-wrapped/src/evaluator.ts
index 9e4d418ef0..1559cb186e 100644
--- a/tools/@angular/tsc-wrapped/src/evaluator.ts
+++ b/tools/@angular/tsc-wrapped/src/evaluator.ts
@@ -442,6 +442,36 @@ export class Evaluator {
           (<MetadataImportedSymbolReferenceExpression>typeReference).arguments = args;
         }
         return recordEntry(typeReference, node);
+      case ts.SyntaxKind.UnionType:
+        const unionType = <ts.UnionTypeNode>node;
+
+        // Remove null and undefined from the list of unions.
+        const references = unionType.types
+                               .filter(
+                                   n => n.kind != ts.SyntaxKind.NullKeyword &&
+                                       n.kind != ts.SyntaxKind.UndefinedKeyword)
+                               .map(n => this.evaluateNode(n));
+
+        // The remmaining reference must be the same. If two have type arguments consider them
+        // different even if the type arguments are the same.
+        let candidate: any = null;
+        for (let i = 0; i < references.length; i++) {
+          const reference = references[i];
+          if (isMetadataSymbolicReferenceExpression(reference)) {
+            if (candidate) {
+              if ((reference as any).name == candidate.name &&
+                  (reference as any).module == candidate.module && !(reference as any).arguments) {
+                candidate = reference;
+              }
+            } else {
+              candidate = reference;
+            }
+          } else {
+            return reference;
+          }
+        }
+        if (candidate) return candidate;
+        break;
       case ts.SyntaxKind.NoSubstitutionTemplateLiteral:
       case ts.SyntaxKind.StringLiteral:
       case ts.SyntaxKind.TemplateHead:
diff --git a/tools/@angular/tsc-wrapped/test/collector.spec.ts b/tools/@angular/tsc-wrapped/test/collector.spec.ts
index 0dddee2509..89e8caee87 100644
--- a/tools/@angular/tsc-wrapped/test/collector.spec.ts
+++ b/tools/@angular/tsc-wrapped/test/collector.spec.ts
@@ -707,6 +707,30 @@ describe('Collector', () => {
     });
   });
 
+  it('should ignore |null or |undefined in type expressions', () => {
+    const source = ts.createSourceFile(
+        'somefile.ts', `
+      import {Foo} from './foo';
+      export class SomeClass {
+        constructor (a: Foo, b: Foo | null, c: Foo | undefined, d: Foo | undefined | null, e: Foo | undefined | null | Foo) {}
+      }
+    `,
+        ts.ScriptTarget.Latest, true);
+    const metadata = collector.getMetadata(source);
+    expect((metadata.metadata['SomeClass'] as ClassMetadata).members).toEqual({
+      __ctor__: [{
+        __symbolic: 'constructor',
+        parameters: [
+          {__symbolic: 'reference', module: './foo', name: 'Foo'},
+          {__symbolic: 'reference', module: './foo', name: 'Foo'},
+          {__symbolic: 'reference', module: './foo', name: 'Foo'},
+          {__symbolic: 'reference', module: './foo', name: 'Foo'},
+          {__symbolic: 'reference', module: './foo', name: 'Foo'}
+        ]
+      }]
+    });
+  });
+
   describe('in strict mode', () => {
     it('should throw if an error symbol is collecting a reference to a non-exported symbol', () => {
       const source = program.getSourceFile('/local-symbol-ref.ts');