diff --git a/packages/core/src/di/injector_compatibility.ts b/packages/core/src/di/injector_compatibility.ts
index 8dc6e32116..402621aef1 100644
--- a/packages/core/src/di/injector_compatibility.ts
+++ b/packages/core/src/di/injector_compatibility.ts
@@ -126,7 +126,7 @@ Please check that 1) the type for the parameter at index ${
  * @param flags Optional flags that control how injection is executed.
  * The flags correspond to injection strategies that can be specified with
  * parameter decorators `@Host`, `@Self`, `@SkipSef`, and `@Optional`.
- * @returns True if injection is successful, null otherwise.
+ * @returns the injected value if injection is successful, `null` otherwise.
  *
  * @usageNotes
  *
diff --git a/packages/core/src/di/metadata.ts b/packages/core/src/di/metadata.ts
index 913f3e8ce8..856ecd308c 100644
--- a/packages/core/src/di/metadata.ts
+++ b/packages/core/src/di/metadata.ts
@@ -71,14 +71,14 @@ export interface OptionalDecorator {
   /**
    * Parameter decorator to be used on constructor parameters,
    * which marks the parameter as being an optional dependency.
-   * The DI framework provides null if the dependency is not found.
+   * The DI framework provides `null` if the dependency is not found.
    *
    * Can be used together with other parameter decorators
    * that modify how dependency injection operates.
    *
    * @usageNotes
    *
-   * The following code allows the possibility of a null result:
+   * The following code allows the possibility of a `null` result:
    *
    * <code-example path="core/di/ts/metadata_spec.ts" region="Optional">
    * </code-example>
@@ -118,7 +118,7 @@ export interface SelfDecorator {
    * which tells the DI framework to start dependency resolution from the local injector.
    *
    * Resolution works upward through the injector hierarchy, so the children
-   * of this class must configure their own providers or be prepared for a null result.
+   * of this class must configure their own providers or be prepared for a `null` result.
    *
    * @usageNotes
    *
@@ -216,7 +216,7 @@ export interface HostDecorator {
    *
    * @usageNotes
    *
-   * The following shows use with the `@Optional` decorator, and allows for a null result.
+   * The following shows use with the `@Optional` decorator, and allows for a `null` result.
    *
    * <code-example path="core/di/ts/metadata_spec.ts" region="Host">
    * </code-example>
@@ -244,4 +244,4 @@ export interface Host {}
 export const Host: HostDecorator =
     // Disable tslint because `InternalInjectFlags` is a const enum which gets inlined.
     // tslint:disable-next-line: no-toplevel-property-access
-    attachInjectFlag(makeParamDecorator('Host'), InternalInjectFlags.Host);
\ No newline at end of file
+    attachInjectFlag(makeParamDecorator('Host'), InternalInjectFlags.Host);