diff --git a/types/memoize-one/v3/index.d.ts b/types/memoize-one/v3/index.d.ts
new file mode 100644
index 0000000000..71f785e73c
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+++ b/types/memoize-one/v3/index.d.ts
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+// Type definitions for memoize-one 3.1
+// Project: https://github.com/alexreardon/memoize-one#readme
+// Definitions by: Karol Majewski <https://github.com/karol-majewski>, Frank Li <https://github.com/franklixuefei>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+declare function memoizeOne<T extends (...args: any[]) => any>(resultFn: T, isEqual?: EqualityFn): T;
+export type EqualityFn = (a: any, b: any) => boolean;
+
+export default memoizeOne;
diff --git a/types/memoize-one/v3/memoize-one-tests.ts b/types/memoize-one/v3/memoize-one-tests.ts
new file mode 100644
index 0000000000..f163add16e
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+++ b/types/memoize-one/v3/memoize-one-tests.ts
@@ -0,0 +1,33 @@
+import memoizeOne, { EqualityFn } from 'memoize-one';
+
+declare function add(a: number, b: number): number ;
+declare function lousyEqualityFn(a: any, b: any): boolean;
+declare function strictEqualityFn<T>(a: T, b: T): boolean;
+
+/**
+ * Accepts a second argument.
+ */
+memoizeOne(add); // $ExpectType (a: number, b: number) => number
+memoizeOne(add, lousyEqualityFn); // $ExpectType (a: number, b: number) => number
+memoizeOne(add, strictEqualityFn); // $ExpectType (a: number, b: number) => number
+
+/**
+ * The second argument can be, but doesn't have to be strictly typed.
+ */
+memoizeOne(add, (a, b) => a === b); // $ExpectType (a: number, b: number) => number
+memoizeOne(add, (a: string, b: string) => a === b); // $ExpectType (a: number, b: number) => number
+
+/**
+ * Function passed as the second argument accepts exactly two arguments.
+ */
+memoizeOne(add, (a: number, b: number, c: number) => a === b || c); // $ExpectError
+
+/**
+ * Function passed as the second argument returns a boolean.
+ */
+memoizeOne(add, (a: string, b: string) => 0); // $ExpectError
+
+/**
+ * The `EqualityFn` type is publicly accessible.
+ */
+const simpleIsEqual: EqualityFn = (x: number, y: number): boolean => (x === y);
diff --git a/types/memoize-one/v3/tsconfig.json b/types/memoize-one/v3/tsconfig.json
new file mode 100644
index 0000000000..728bd3ee58
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+++ b/types/memoize-one/v3/tsconfig.json
@@ -0,0 +1,26 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../../",
+        "typeRoots": [
+            "../../"
+        ],
+        "types": [],
+        "paths": {
+            "memoize-one": [ "memoize-one/v3" ]
+        },
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "memoize-one-tests.ts"
+    ]
+}
diff --git a/types/memoize-one/v3/tslint.json b/types/memoize-one/v3/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/memoize-one/v3/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }