diff --git a/pkg/analyzer/lib/error/error.dart b/pkg/analyzer/lib/error/error.dart
index 0e9ad7b77e0..3b4ccac8e45 100644
--- a/pkg/analyzer/lib/error/error.dart
+++ b/pkg/analyzer/lib/error/error.dart
@@ -59,6 +59,7 @@ const List<ErrorCode> errorCodeValues = const [
   CompileTimeErrorCode.ARGUMENT_DEFINITION_TEST_NON_PARAMETER,
   CompileTimeErrorCode.ASYNC_FOR_IN_WRONG_CONTEXT,
   CompileTimeErrorCode.AWAIT_IN_WRONG_CONTEXT,
+  CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_PREFIX_NAME,
   CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE,
   CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPEDEF_NAME,
   CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME,
diff --git a/pkg/analyzer/lib/src/error/codes.dart b/pkg/analyzer/lib/src/error/codes.dart
index 8171fa6ab13..c31595032fe 100644
--- a/pkg/analyzer/lib/src/error/codes.dart
+++ b/pkg/analyzer/lib/src/error/codes.dart
@@ -248,6 +248,20 @@ class CompileTimeErrorCode extends ErrorCode {
           "The await expression can only be used in an asynchronous function.",
           "Try marking the function body with either 'async' or 'async*'.");
 
+  /**
+   * 16.33 Identifier Reference: It is a compile-time error if a built-in
+   * identifier is used as the declared name of a prefix, class, type parameter
+   * or type alias.
+   *
+   * Parameters:
+   * 0: the built-in identifier that is being used
+   */
+  static const CompileTimeErrorCode BUILT_IN_IDENTIFIER_AS_PREFIX_NAME =
+      const CompileTimeErrorCode(
+          'BUILT_IN_IDENTIFIER_AS_PREFIX_NAME',
+          "The built-in identifier '{0}' can't be used as a prefix name.",
+          "Try choosing a different name for the prefix.");
+
   /**
    * 12.30 Identifier Reference: It is a compile-time error to use a built-in
    * identifier other than dynamic as a type annotation.
@@ -262,9 +276,9 @@ class CompileTimeErrorCode extends ErrorCode {
           "Try correcting the name to match an existing type.");
 
   /**
-   * 12.30 Identifier Reference: It is a compile-time error if a built-in
-   * identifier is used as the declared name of a class, type parameter or type
-   * alias.
+   * 16.33 Identifier Reference: It is a compile-time error if a built-in
+   * identifier is used as the declared name of a prefix, class, type parameter
+   * or type alias.
    *
    * Parameters:
    * 0: the built-in identifier that is being used
@@ -276,9 +290,9 @@ class CompileTimeErrorCode extends ErrorCode {
           "Try choosing a different name for the type.");
 
   /**
-   * 12.30 Identifier Reference: It is a compile-time error if a built-in
-   * identifier is used as the declared name of a class, type parameter or type
-   * alias.
+   * 16.33 Identifier Reference: It is a compile-time error if a built-in
+   * identifier is used as the declared name of a prefix, class, type parameter
+   * or type alias.
    *
    * Parameters:
    * 0: the built-in identifier that is being used
@@ -290,9 +304,9 @@ class CompileTimeErrorCode extends ErrorCode {
           "Try choosing a different name for the typedef.");
 
   /**
-   * 12.30 Identifier Reference: It is a compile-time error if a built-in
-   * identifier is used as the declared name of a class, type parameter or type
-   * alias.
+   * 16.33 Identifier Reference: It is a compile-time error if a built-in
+   * identifier is used as the declared name of a prefix, class, type parameter
+   * or type alias.
    *
    * Parameters:
    * 0: the built-in identifier that is being used
diff --git a/pkg/analyzer/lib/src/generated/error_verifier.dart b/pkg/analyzer/lib/src/generated/error_verifier.dart
index c9bcf4350f7..1fa5eae09db 100644
--- a/pkg/analyzer/lib/src/generated/error_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/error_verifier.dart
@@ -900,6 +900,10 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
   @override
   Object visitImportDirective(ImportDirective node) {
     ImportElement importElement = node.element;
+    if (node.prefix != null) {
+      _checkForBuiltInIdentifierAsName(
+          node.prefix, CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_PREFIX_NAME);
+    }
     if (importElement != null) {
       _checkForImportDuplicateLibraryName(node, importElement);
       _checkForImportInternalLibrary(node, importElement);
diff --git a/pkg/analyzer/test/generated/compile_time_error_code_test.dart b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
index 3c95c9da539..a8b21c98948 100644
--- a/pkg/analyzer/test/generated/compile_time_error_code_test.dart
+++ b/pkg/analyzer/test/generated/compile_time_error_code_test.dart
@@ -624,6 +624,16 @@ class as = A with B;''');
     verify([source]);
   }
 
+  test_builtInIdentifierAsPrefixName() async {
+    Source source = addSource("import 'dart:async' as abstract;");
+    await computeAnalysisResult(source);
+    assertErrors(source, [
+      CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_PREFIX_NAME,
+      HintCode.UNUSED_IMPORT
+    ]);
+    verify([source]);
+  }
+
   test_builtInIdentifierAsType_formalParameter_field() async {
     Source source = addSource(r'''
 class A {
diff --git a/pkg/analyzer/test/generated/non_error_resolver_test.dart b/pkg/analyzer/test/generated/non_error_resolver_test.dart
index 21568ccad12..f9c5a45f0b5 100644
--- a/pkg/analyzer/test/generated/non_error_resolver_test.dart
+++ b/pkg/analyzer/test/generated/non_error_resolver_test.dart
@@ -2195,17 +2195,6 @@ class B {
     verify([source]);
   }
 
-  test_implicitThisReferenceInInitializer_importPrefix() async {
-    Source source = addSource(r'''
-import 'dart:async' as abstract;
-class A {
-  var v = new abstract.Completer();
-}''');
-    await computeAnalysisResult(source);
-    assertNoErrors(source);
-    verify([source]);
-  }
-
   test_implicitThisReferenceInInitializer_prefixedIdentifier() async {
     Source source = addSource(r'''
 class A {
diff --git a/tests/co19/co19-analyzer2.status b/tests/co19/co19-analyzer2.status
index 58406e63d9b..b6aac2262f4 100644
--- a/tests/co19/co19-analyzer2.status
+++ b/tests/co19/co19-analyzer2.status
@@ -26,22 +26,6 @@ Language/Expressions/Function_Invocation/Unqualified_Invocation/instance_context
 Language/Expressions/Function_Invocation/Unqualified_Invocation/instance_context_invocation_t04: MissingCompileTimeError # Please triage this failure.
 Language/Expressions/Function_Invocation/Unqualified_Invocation/invocation_t17: MissingCompileTimeError # Please triage this failure
 Language/Expressions/Function_Invocation/Unqualified_Invocation/invocation_t18: MissingCompileTimeError # Please triage this failure
-Language/Expressions/Identifier_Reference/built_in_identifier_t53: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t54: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t55: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t56: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t57: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t58: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t59: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t60: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t61: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t62: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t63: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t64: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t65: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t66: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t67: MissingCompileTimeError # Issue 25733
-Language/Expressions/Identifier_Reference/built_in_identifier_t68: MissingCompileTimeError # Issue 25733
 Language/Expressions/Identifier_Reference/built_in_not_dynamic_t17: MissingCompileTimeError # Please triage this failure.
 Language/Expressions/Identifier_Reference/built_in_not_dynamic_t18: MissingCompileTimeError # Please triage this failure.
 Language/Expressions/Identifier_Reference/built_in_not_dynamic_t19: MissingCompileTimeError # Please triage this failure.