diff --git a/types/reservoir/index.d.ts b/types/reservoir/index.d.ts
new file mode 100644
index 0000000000..b08e8aebfa
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+++ b/types/reservoir/index.d.ts
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+// Type definitions for reservoir 0.1
+// Project: https://github.com/imbcmdth/reservoir
+// Definitions by: Dan Vanderkam <https://github.com/danvk>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+export as namespace Reservoir;
+export = Reservoir;
+
+/**
+ * Create a new reservoir sampler.
+ *
+ * @param reservoirSize is the maximum size of the reservoir. This is the number of elements
+ *   to be randomly chosen from the input provided to it using pushSome. Default is 1.
+ * @param randomNumberGenerator is an optional random number generating function to use in
+ *   place of the default Math.random.
+ */
+declare function Reservoir<T>(
+    reservoirSize?: number,
+    randomNumberGenerator?: () => number
+): Reservoir.ReservoirArray<T>;  // tslint:disable-line:no-unnecessary-generics
+
+/*~ If you want to expose types from your module as well, you can
+ *~ place them in this block. Often you will want to describe the
+ *~ shape of the return type of the function; that type should
+ *~ be declared in here, as this example shows.
+ */
+declare namespace Reservoir {
+    interface ReservoirArray<T> extends Array<T> {
+        /**
+         * datum: one or more elements to consider for inclusion into the reservoir.
+         * Returns the current length of the reservoir.
+         */
+        pushSome(...datum: T[]): number;
+    }
+}
diff --git a/types/reservoir/reservoir-tests.ts b/types/reservoir/reservoir-tests.ts
new file mode 100644
index 0000000000..f7775bd1bb
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+++ b/types/reservoir/reservoir-tests.ts
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+import Reservoir = require('reservoir');
+
+// $ExpectType ReservoirArray<number>
+const x = Reservoir<number>(1);
+
+// $ExpectType number
+x.pushSome(10, 20, 30, 40);
+
+// $ExpectType number
+x[0];
+
+// $ExpectType number
+x.length;
diff --git a/types/reservoir/tsconfig.json b/types/reservoir/tsconfig.json
new file mode 100644
index 0000000000..ff04e5c9d5
--- /dev/null
+++ b/types/reservoir/tsconfig.json
@@ -0,0 +1,24 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true,
+        "esModuleInterop": true
+    },
+    "files": [
+        "index.d.ts",
+        "reservoir-tests.ts"
+    ]
+}
diff --git a/types/reservoir/tslint.json b/types/reservoir/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
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+++ b/types/reservoir/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }