diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 457502f4c14..53d77338024 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -2797,6 +2797,7 @@ namespace ts {
             // If this is a property-parameter, then also declare the property symbol into the
             // containing class.
             if (isParameterPropertyDeclaration(node)) {
+                // tslint:disable-next-line no-unnecessary-type-assertion
                 const classDeclaration = <ClassLikeDeclaration>node.parent.parent;
                 declareSymbol(classDeclaration.symbol.members!, classDeclaration.symbol, node, SymbolFlags.Property | (node.questionToken ? SymbolFlags.Optional : SymbolFlags.None), SymbolFlags.PropertyExcludes);
             }
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3b70ce8da11..d0c99aada0c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -9684,6 +9684,7 @@ namespace ts {
                         break;
                 }
             }
+            // tslint:disable-next-line no-unnecessary-type-assertion
             return links.resolvedType!; // TODO: GH#18217
         }
 
@@ -25738,7 +25739,9 @@ namespace ts {
                 if (node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement) {
                     checkVarDeclaredNamesNotShadowed(node);
                 }
+                // tslint:disable-next-line no-unnecessary-type-assertion
                 checkCollisionWithRequireExportsInGeneratedCode(node, <Identifier>node.name);
+                // tslint:disable-next-line no-unnecessary-type-assertion
                 checkCollisionWithGlobalPromiseInGeneratedCode(node, <Identifier>node.name);
             }
         }
@@ -30401,9 +30404,11 @@ namespace ts {
                     node.kind === SyntaxKind.FunctionExpression ||
                     node.kind === SyntaxKind.MethodDeclaration);
                 if (node.flags & NodeFlags.Ambient) {
+                    // tslint:disable-next-line no-unnecessary-type-assertion
                     return grammarErrorOnNode(node.asteriskToken!, Diagnostics.Generators_are_not_allowed_in_an_ambient_context);
                 }
                 if (!node.body) {
+                    // tslint:disable-next-line no-unnecessary-type-assertion
                     return grammarErrorOnNode(node.asteriskToken!, Diagnostics.An_overload_signature_cannot_be_declared_as_a_generator);
                 }
             }
@@ -30444,6 +30449,7 @@ namespace ts {
 
                 // Modifiers are never allowed on properties except for 'async' on a method declaration
                 if (prop.modifiers) {
+                    // tslint:disable-next-line no-unnecessary-type-assertion
                     for (const mod of prop.modifiers!) { // TODO: GH#19955
                         if (mod.kind !== SyntaxKind.AsyncKeyword || prop.kind !== SyntaxKind.MethodDeclaration) {
                             grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod));
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 8baeae5d84a..242a5f4eda5 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -251,6 +251,7 @@ namespace ts {
                     // Explicitly do not passthru either `inline` option
                 });
                 if (emitOnlyDtsFiles && declarationTransform.transformed[0].kind === SyntaxKind.SourceFile) {
+                    // tslint:disable-next-line no-unnecessary-type-assertion
                     const sourceFile = declarationTransform.transformed[0] as SourceFile;
                     exportedModulesFromDeclarationEmit = sourceFile.exportedModulesFromDeclarationEmit;
                 }
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index f0c6ec93366..e45b43a7209 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -3489,10 +3489,12 @@ namespace ts {
                         }
 
                         if (member.kind === SyntaxKind.GetAccessor && !getAccessor) {
+                            // tslint:disable-next-line no-unnecessary-type-assertion
                             getAccessor = <GetAccessorDeclaration>member;
                         }
 
                         if (member.kind === SyntaxKind.SetAccessor && !setAccessor) {
+                            // tslint:disable-next-line no-unnecessary-type-assertion
                             setAccessor = <SetAccessorDeclaration>member;
                         }
                     }