diff --git a/lib/lib.es5.d.ts b/lib/lib.es5.d.ts
index d1a9d6f0d2afe..3c96997538d20 100644
--- a/lib/lib.es5.d.ts
+++ b/lib/lib.es5.d.ts
@@ -1039,6 +1039,11 @@ interface URIErrorConstructor {
 
 declare const URIError: URIErrorConstructor;
 
+type JSONPrimitive = string | number | boolean | null;
+type JSONValue = JSONPrimitive | JSONObject | JSONArray;
+type JSONObject = { [member: string]: JSONValue };
+interface JSONArray extends Array<JSONValue> {}
+
 interface JSON {
     /**
       * Converts a JavaScript Object Notation (JSON) string into an object.
@@ -1046,7 +1051,7 @@ interface JSON {
       * @param reviver A function that transforms the results. This function is called for each member of the object.
       * If a member contains nested objects, the nested objects are transformed before the parent object is.
       */
-    parse(text: string, reviver?: (key: any, value: any) => any): any;
+    parse(text: string, reviver?: (key: any, value: any) => any): JSONValue;
     /**
       * Converts a JavaScript value to a JavaScript Object Notation (JSON) string.
       * @param value A JavaScript value, usually an object or array, to be converted.
diff --git a/scripts/configurePrerelease.ts b/scripts/configurePrerelease.ts
index 93bcc004deab6..111be6b2e66bd 100644
--- a/scripts/configurePrerelease.ts
+++ b/scripts/configurePrerelease.ts
@@ -28,7 +28,7 @@ function main(): void {
 
     // Acquire the version from the package.json file and modify it appropriately.
     const packageJsonFilePath = normalize(args[1]);
-    const packageJsonValue: PackageJson = JSON.parse(readFileSync(packageJsonFilePath).toString());
+    const packageJsonValue = JSON.parse(readFileSync(packageJsonFilePath).toString()) as PackageJson;
 
     const { majorMinor, patch } = parsePackageJsonVersion(packageJsonValue.version);
     const prereleasePatch = getPrereleasePatch(tag, patch);
diff --git a/scripts/generateLocalizedDiagnosticMessages.ts b/scripts/generateLocalizedDiagnosticMessages.ts
index 09d117d533ba4..d94fdb815562d 100644
--- a/scripts/generateLocalizedDiagnosticMessages.ts
+++ b/scripts/generateLocalizedDiagnosticMessages.ts
@@ -136,7 +136,7 @@ function main(): void {
             writeFile(
                 path.join(outputPath, "enu", "diagnosticMessages.generated.json.lcg"),
                 getLCGFileXML(
-                    objectToList(JSON.parse(data.toString()))
+                    objectToList(JSON.parse(data.toString()) as Record<string, string>)
                         .sort((a, b) => a.key > b.key ? 1 : -1)  // lcg sorted by property keys
                         .reduce((s, { key, value }) => s + getItemXML(key, value), "")
                 ));
diff --git a/scripts/processDiagnosticMessages.ts b/scripts/processDiagnosticMessages.ts
index f296a62de78ed..82a8fe5935742 100644
--- a/scripts/processDiagnosticMessages.ts
+++ b/scripts/processDiagnosticMessages.ts
@@ -27,7 +27,7 @@ function main(): void {
     console.log(`Reading diagnostics from ${inputFilePath}`);
     const inputStr = fs.readFileSync(inputFilePath, { encoding: "utf-8" });
 
-    const diagnosticMessagesJson: { [key: string]: DiagnosticDetails } = JSON.parse(inputStr);
+    const diagnosticMessagesJson = JSON.parse(inputStr) as { [key: string]: DiagnosticDetails };
 
     const diagnosticMessages: InputDiagnosticMessageTable = new Map();
     for (const key in diagnosticMessagesJson) {