diff --git a/.eslintrc b/.eslintrc
index 9d473154a84..769447e1295 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -46,7 +46,7 @@
         "@typescript-eslint/prefer-interface": "off",
         "@typescript-eslint/prefer-namespace-keyword": "off",
         "semi": "off",
-        "@typescript-eslint/semi": "off",
+        "@typescript-eslint/semi": "error",
         "@typescript-eslint/type-annotation-spacing": "off",
         "@typescript-eslint/unified-signatures": "off",
 
diff --git a/scripts/authors.ts b/scripts/authors.ts
index f92511ed6ef..c05d7106913 100644
--- a/scripts/authors.ts
+++ b/scripts/authors.ts
@@ -71,7 +71,7 @@ function getKnownAuthorMaps() {
 }
 
 function deduplicate<T>(array: T[]): T[] {
-    let result: T[] = []
+    let result: T[] = [];
     if (array) {
         for (const item of array) {
             if (result.indexOf(item) < 0) {
diff --git a/scripts/buildProtocol.ts b/scripts/buildProtocol.ts
index 006608323cf..08dd56b5657 100644
--- a/scripts/buildProtocol.ts
+++ b/scripts/buildProtocol.ts
@@ -28,11 +28,11 @@ class DeclarationsWalker {
             : "";
         if (walker.removedTypes) {
             text += "\ndeclare namespace ts {\n";
-            text += "    // these types are empty stubs for types from services and should not be used directly\n"
+            text += "    // these types are empty stubs for types from services and should not be used directly\n";
             for (const type of walker.removedTypes) {
                 text += `    export type ${type.symbol!.name} = never;\n`;
             }
-            text += "}"
+            text += "}";
         }
         return text;
     }
@@ -142,7 +142,7 @@ function writeProtocolFile(outputFile: string, protocolTs: string, typeScriptSer
                 getCanonicalFileName: function (f) { return f; },
                 getCurrentDirectory: function() { return '.'; },
                 getNewLine: function() { return "\r\n"; }
-            }
+            };
             const diags = emitResult.diagnostics.map(d => ts.formatDiagnostic(d, diagHost)).join("\r\n");
             throw new Error(`Declaration file for protocol.ts is not generated:\r\n${diags}`);
         }
@@ -161,7 +161,7 @@ function writeProtocolFile(outputFile: string, protocolTs: string, typeScriptSer
                 return ts.createSourceFile(fileName, protocolDts, options.target);
             }
             return originalGetSourceFile.apply(host, [fileName]);
-        }
+        };
         const rootFiles = includeTypeScriptServices ? [protocolFileName, typeScriptServicesDts] : [protocolFileName];
         return ts.createProgram(rootFiles, options, host);
     }
diff --git a/scripts/configurePrerelease.ts b/scripts/configurePrerelease.ts
index 5e3ac5653d7..68befbb8bcd 100644
--- a/scripts/configurePrerelease.ts
+++ b/scripts/configurePrerelease.ts
@@ -48,7 +48,7 @@ function main(): void {
     // Finally write the changes to disk.
     // Modify the package.json structure
     packageJsonValue.version = `${majorMinor}.${prereleasePatch}`;
-    writeFileSync(packageJsonFilePath, JSON.stringify(packageJsonValue, /*replacer:*/ undefined, /*space:*/ 4))
+    writeFileSync(packageJsonFilePath, JSON.stringify(packageJsonValue, /*replacer:*/ undefined, /*space:*/ 4));
     writeFileSync(tsFilePath, modifiedTsFileContents);
 }
 
diff --git a/scripts/importDefinitelyTypedTests/importDefinitelyTypedTests.ts b/scripts/importDefinitelyTypedTests/importDefinitelyTypedTests.ts
index 1ae3725fff2..e984a72a2d0 100644
--- a/scripts/importDefinitelyTypedTests/importDefinitelyTypedTests.ts
+++ b/scripts/importDefinitelyTypedTests/importDefinitelyTypedTests.ts
@@ -11,16 +11,16 @@ declare var process: {
     argv: string[];
     env: Map<string>;
     exit(exitCode?: number): void;
-}
+};
 
 main();
 function main() {
     const [, progName, tscRoot, definitelyTypedRoot] = process.argv;
     if (process.argv.length !== 4) {
         if (process.argv.length < 2) {
-            throw "Expected at least 2 argv elements."
+            throw "Expected at least 2 argv elements.";
         }
-        console.log("Usage:")
+        console.log("Usage:");
         console.log(`    node ${path.relative(__dirname, progName)} [TypeScript Repo Root] [DefinitelyTyped Repo Root]`);
         return;
     }
@@ -52,7 +52,7 @@ function importDefinitelyTypedTest(tscPath: string, rwcTestPath: string, testCas
         cmd += " @" + responseFile;
     }
 
-    let testDirectoryName = testCaseName + "_" + Math.floor((Math.random() * 10000) + 1); 
+    let testDirectoryName = testCaseName + "_" + Math.floor((Math.random() * 10000) + 1);
     let testDirectoryPath = path.join(process.env["temp"], testDirectoryName);
     if (fs.existsSync(testDirectoryPath)) {
         throw new Error("Could not create test directory");
@@ -156,6 +156,6 @@ function importDefinitelyTypedTests(tscPath: string, rwcTestPath: string, defini
                         }
                     }
                 });
-            })
+            });
     });
-}
\ No newline at end of file
+}
diff --git a/scripts/open-cherry-pick-pr.ts b/scripts/open-cherry-pick-pr.ts
index 8bdeb05e4a2..eed8f33d374 100644
--- a/scripts/open-cherry-pick-pr.ts
+++ b/scripts/open-cherry-pick-pr.ts
@@ -34,7 +34,7 @@ async function main() {
     logText = `Cherry-pick PR #${process.env.SOURCE_ISSUE} into ${process.env.TARGET_BRANCH}
 
 Component commits:
-${logText.trim()}`
+${logText.trim()}`;
     const logpath = path.join(__dirname, "../", "logmessage.txt");
     runSequence([
         ["git", ["checkout", "-b", "temp-branch"]],
@@ -51,7 +51,7 @@ ${logText.trim()}`
     runSequence([
         ["git", ["checkout", process.env.TARGET_BRANCH]], // checkout the target branch
         ["git", ["checkout", "-b", branchName]], // create a new branch
-        ["git", ["cherry-pick", squashSha.trim()]], // 
+        ["git", ["cherry-pick", squashSha.trim()]], //
         ["git", ["remote", "add", "fork", remoteUrl]], // Add the remote fork
         ["git", ["push", "--set-upstream", "fork", branchName, "-f"]] // push the branch
     ]);
@@ -102,4 +102,4 @@ main().catch(async e => {
             body: `Hey @${process.env.REQUESTING_USER}, I couldn't open a PR with the cherry-pick. ([You can check the log here](https://typescript.visualstudio.com/TypeScript/_build/index?buildId=${process.env.BUILD_BUILDID}&_a=summary)). You may need to squash and pick this PR into ${process.env.TARGET_BRANCH} manually.`
         });
     }
-});
\ No newline at end of file
+});
diff --git a/scripts/processDiagnosticMessages.ts b/scripts/processDiagnosticMessages.ts
index f296a62de78..cc93117f4d0 100644
--- a/scripts/processDiagnosticMessages.ts
+++ b/scripts/processDiagnosticMessages.ts
@@ -20,7 +20,7 @@ function main(): void {
     function writeFile(fileName: string, contents: string) {
         fs.writeFile(path.join(path.dirname(inputFilePath), fileName), contents, { encoding: "utf-8" }, err => {
             if (err) throw err;
-        })
+        });
     }
 
     const inputFilePath = process.argv[2].replace(/\\/g, "/");
diff --git a/src/typingsInstaller/nodeTypingsInstaller.ts b/src/typingsInstaller/nodeTypingsInstaller.ts
index 27be0107d8f..56b490e709d 100644
--- a/src/typingsInstaller/nodeTypingsInstaller.ts
+++ b/src/typingsInstaller/nodeTypingsInstaller.ts
@@ -15,7 +15,7 @@ namespace ts.server.typingsInstaller {
 
         isEnabled = () => {
             return typeof this.logFile === "string";
-        }
+        };
         writeLine = (text: string) => {
             if (typeof this.logFile !== "string") return;
 
@@ -25,7 +25,7 @@ namespace ts.server.typingsInstaller {
             catch (e) {
                 this.logFile = undefined;
             }
-        }
+        };
     }
 
     /** Used if `--npmLocation` is not passed. */