diff --git a/modules/@angular/common/src/pipes/lowercase_pipe.ts b/modules/@angular/common/src/pipes/lowercase_pipe.ts
index 6f2ba88de0..037c211cf8 100644
--- a/modules/@angular/common/src/pipes/lowercase_pipe.ts
+++ b/modules/@angular/common/src/pipes/lowercase_pipe.ts
@@ -17,7 +17,7 @@ import {InvalidPipeArgumentError} from './invalid_pipe_argument_error';
  * @howToUse `expression | lowercase`
  * @description
  *
- * Converts value into lowercase string using `String.prototype.toLowerCase()`.
+ * Converts value into a lowercase string using `String.prototype.toLowerCase()`.
  *
  * ### Example
  *
diff --git a/modules/@angular/common/src/pipes/uppercase_pipe.ts b/modules/@angular/common/src/pipes/uppercase_pipe.ts
index 9cce72c008..fdfeceb9c8 100644
--- a/modules/@angular/common/src/pipes/uppercase_pipe.ts
+++ b/modules/@angular/common/src/pipes/uppercase_pipe.ts
@@ -16,7 +16,7 @@ import {InvalidPipeArgumentError} from './invalid_pipe_argument_error';
  * @howToUse `expression | uppercase`
  * @description
  *
- * Converts value into lowercase string using `String.prototype.toUpperCase()`.
+ * Converts value into an uppercase string using `String.prototype.toUpperCase()`.
  *
  * ### Example
  *