diff --git a/types/fixed-data-table-2/fixed-data-table-2-tests.tsx b/types/fixed-data-table-2/fixed-data-table-2-tests.tsx
index ba89f504a3b5b1..855ac6ba1b95d7 100644
--- a/types/fixed-data-table-2/fixed-data-table-2-tests.tsx
+++ b/types/fixed-data-table-2/fixed-data-table-2-tests.tsx
@@ -181,8 +181,8 @@ class MyTable5 extends React.Component {
                 headerHeight={50}
                 width={1000}
                 height={500}
-                onScrollStart={(x: number, y: number) => {}}
-                onScrollEnd={(x: number, y: number) => {}}
+                onScrollStart={(x: number, y: number, firstRowIndex: number, lastRowIndex: number) => {}}
+                onScrollEnd={(x: number, y: number, firstRowIndex: number, lastRowIndex: number) => {}}
                 onContentHeightChange={(newHeight: number) => {}}
                 onRowClick={(event: React.SyntheticEvent<Table>, rowIndex: number) => {}}
                 onRowContextMenu={(event: React.SyntheticEvent<Table>, rowIndex: number) => {}}
diff --git a/types/fixed-data-table-2/index.d.ts b/types/fixed-data-table-2/index.d.ts
index b9297a1bf3ab7e..9d17f34fb93802 100644
--- a/types/fixed-data-table-2/index.d.ts
+++ b/types/fixed-data-table-2/index.d.ts
@@ -272,15 +272,15 @@ export interface TableProps extends React.ClassAttributes<Table> {
 
     /**
      * Callback that is called when scrolling starts with current horizontal
-     * and vertical scroll values.
+     * and vertical scroll values, as well as the first and last row index.
      */
-    onScrollStart?: ((x: number, y: number) => void) | undefined;
+    onScrollStart?: ((x: number, y: number, firstRowIndex: number, lastRowIndex: number) => void) | undefined;
 
     /**
      * Callback that is called when scrolling ends or stops with new horizontal
-     * and vertical scroll values.
+     * and vertical scroll values, as well as the first and last row index.
      */
-    onScrollEnd?: ((x: number, y: number) => void) | undefined;
+    onScrollEnd?: ((x: number, y: number, firstRowIndex: number, lastRowIndex: number) => void) | undefined;
 
     /**
      * If enabled scroll events will not be propagated outside of the table.
diff --git a/types/memoizee/index.d.ts b/types/memoizee/index.d.ts
index 69ef17b4e4c706..88f79fdada183f 100644
--- a/types/memoizee/index.d.ts
+++ b/types/memoizee/index.d.ts
@@ -13,9 +13,9 @@ declare namespace memoizee {
         profileName?: string;
     }
 
-    interface Memoized<F> {
-        delete: F;
-        clear: F & (() => void);
+    interface Memoized<F extends (...args: any[]) => any> {
+        delete: (...args: Parameters<F>) => void;
+        clear: () => void;
     }
 }
 
diff --git a/types/memoizee/memoizee-tests.ts b/types/memoizee/memoizee-tests.ts
index 1bceb95bcc8fe5..5c6c6689c4d6ae 100644
--- a/types/memoizee/memoizee-tests.ts
+++ b/types/memoizee/memoizee-tests.ts
@@ -1,6 +1,8 @@
 import memoize = require("memoizee");
 
-const fn = (one: string, two?: number, three?: any) => {/* ... */};
+const fn = (one: string, two?: number, three?: any) => {
+    return "test";
+};
 
 let memoized = memoize(fn);
 memoized("foo", 3, "bar");
@@ -19,11 +21,30 @@ memoized = memoize(fn, { primitive: true });
 memoized("/path/one");
 memoized("/path/one");
 memoized = memoize(fn, { dispose(value: number) {/*…*/} });
-const foo3 = memoized("foo", 3);
-const bar7 = memoized("bar", 7);
-memoized.clear("foo", 3); // Dispose called with foo3 value
-memoized.clear("bar", 7); // Dispose called with bar7 value
-memoized.delete("foo", 0);
+const foo3: string = memoized("foo", 3);
+const bar7: string = memoized("bar", 7);
+memoized.delete("foo", 3); // Dispose called with foo3 value
+memoized.delete("bar", 7); // Dispose called with bar7 value
+memoized.clear();
+
+function testIncorrectParameterType(): string {
+    // @ts-expect-error Expect TypeScript to error when passing parameters of wrong types.
+    return memoized(3, "foo");
+}
+function testIncorrectDeleteParameterType(): void {
+    // @ts-expect-error Expect TypeScript to error when passing parameters of wrong types.
+    return memoized.delete(3, "foo");
+}
+function testIncorrectClearParameterType(): void {
+    // @ts-expect-error Expect TypeScript since clear() does not take any parameters.
+    return memoized.clear("foo", 3);
+}
+function testDeleteReturnType(a: string, b: number): void {
+    return memoized.delete(a, b);
+}
+function testClearReturnType(): void {
+    return memoized.clear();
+}
 const mFn = memoize((hash: any) => {
     // body of memoized function
 }, {
@@ -49,13 +70,20 @@ memoized(
 
 {
     const afn = (a: number, b: number) => {
-        return new Promise(res => {
+        return new Promise<number>(res => {
             res(a + b);
         });
     };
     let memoized = memoize(afn, { promise: true });
-    memoized(3, 7);
-    memoized(3, 7);
+    const foo: Promise<number> = memoized(3, 7);
+    const bar: Promise<number> = memoized(3, 7);
+
+    function testDeleteReturnType(a: number, b: number): void {
+        return memoized.delete(a, b);
+    }
+    function testClearReturnType(): void {
+        return memoized.clear();
+    }
 
     memoized = memoize(afn, { promise: "then" });
     memoized(2, 7);