diff --git a/src/analysis/output.js b/src/analysis/output.js
index 57f1012..844df93 100644
--- a/src/analysis/output.js
+++ b/src/analysis/output.js
@@ -9,7 +9,6 @@ import {NodeAddress} from "../core/graph";
 import type {Alias} from "../plugins/identity/alias";
 import type {PluginDeclaration} from "./pluginDeclaration";
 import type {TimestampMs} from "../util/timestamp";
-import * as Timestamp from "../util/timestamp";
 import {TimelineCred} from "./timeline/timelineCred";
 import {nodeWeightEvaluator} from "../core/algorithm/weightEvaluator";
 
@@ -66,14 +65,12 @@ export function fromTimelineCredAndPlugins(
       // know what period to mint it in.
       // When we transition to CredRank, we should remove this check.
       const minted = timestampMs == null ? 0 : nodeEvaluator(address);
-      const timestamp =
-        timestampMs == null ? null : Timestamp.fromNumber(timestampMs);
       return {
         address: NodeAddress.toParts(address),
         cred,
         minted,
         description,
-        timestamp,
+        timestamp: timestampMs,
       };
     }
   );
diff --git a/src/plugins/initiatives/createGraph.test.js b/src/plugins/initiatives/createGraph.test.js
index c22d139..7ac0408 100644
--- a/src/plugins/initiatives/createGraph.test.js
+++ b/src/plugins/initiatives/createGraph.test.js
@@ -7,7 +7,6 @@ import {
   NodeAddress,
 } from "../../core/graph";
 import * as Weights from "../../core/weights";
-import * as Timestamp from "../../util/timestamp";
 import sortBy from "../../util/sortBy";
 import type {ReferenceDetector, URL} from "../../core/references";
 import {createWeightedGraph, initiativeWeight} from "./createGraph";
@@ -30,7 +29,7 @@ import {
 const exampleEntry = (overrides: $Shape<NodeEntry>): NodeEntry => ({
   key: overrides.title ? _titleSlug(overrides.title) : "sample-title",
   title: "Sample title",
-  timestampMs: Timestamp.fromNumber(123),
+  timestampMs: 123,
   contributors: [],
   weight: 456,
   ...overrides,
@@ -40,7 +39,7 @@ function _createInitiative(overrides?: $Shape<Initiative>): Initiative {
   return {
     id: createId("UNSET_SUBTYPE", "42"),
     title: "Unset test initiative",
-    timestampMs: Timestamp.fromNumber(123),
+    timestampMs: 123,
     completed: false,
     contributions: {urls: [], entries: []},
     dependencies: {urls: [], entries: []},
@@ -66,7 +65,7 @@ class MockInitiativeRepository implements InitiativeRepository {
     const initiative = _createInitiative({
       id: createId("TEST_SUBTYPE", String(num)),
       title: `Example Initiative ${num}`,
-      timestampMs: Timestamp.fromNumber(400 + num),
+      timestampMs: 400 + num,
       ...shape,
     });
 
diff --git a/src/plugins/initiatives/edgeSpec.test.js b/src/plugins/initiatives/edgeSpec.test.js
index 7900007..5a98ade 100644
--- a/src/plugins/initiatives/edgeSpec.test.js
+++ b/src/plugins/initiatives/edgeSpec.test.js
@@ -1,7 +1,6 @@
 // @flow
 
 import {type TimestampMs} from "../../util/timestamp";
-import * as Timestamp from "../../util/timestamp";
 import {type NodeEntry} from "./nodeEntry";
 import {
   type EdgeSpec,
@@ -14,7 +13,7 @@ import {
 const exampleEntry = (overrides: $Shape<NodeEntry>): NodeEntry => ({
   key: "sample-title",
   title: "Sample title",
-  timestampMs: Timestamp.fromNumber(123),
+  timestampMs: 123,
   contributors: [],
   weight: 456,
   ...overrides,
@@ -23,7 +22,7 @@ const exampleEntry = (overrides: $Shape<NodeEntry>): NodeEntry => ({
 describe("plugins/initiatives/edgeSpec", () => {
   describe("normalizeEdgeSpec", () => {
     it("should add empty arrays when missing", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(321);
+      const timestampMs: TimestampMs = 321;
       const json: EdgeSpecJson = {};
 
       const actual = normalizeEdgeSpec(json, timestampMs);
@@ -31,7 +30,7 @@ describe("plugins/initiatives/edgeSpec", () => {
     });
 
     it("should preserve urls when present", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(321);
+      const timestampMs: TimestampMs = 321;
       const json: EdgeSpecJson = {
         urls: ["https://foo.bar/a", "https://foo.bar/b"],
       };
@@ -41,7 +40,7 @@ describe("plugins/initiatives/edgeSpec", () => {
     });
 
     it("should normalize any entries from json format", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(321);
+      const timestampMs: TimestampMs = 321;
       const json: EdgeSpecJson = {
         entries: [{title: "Minimal example"}],
       };
@@ -62,7 +61,7 @@ describe("plugins/initiatives/edgeSpec", () => {
     });
 
     it("should throw on entries with the same key", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(321);
+      const timestampMs: TimestampMs = 321;
       const json: EdgeSpecJson = {
         entries: [
           {key: "1", title: "first"},
diff --git a/src/plugins/initiatives/nodeEntry.test.js b/src/plugins/initiatives/nodeEntry.test.js
index e3bd0ea..e20f543 100644
--- a/src/plugins/initiatives/nodeEntry.test.js
+++ b/src/plugins/initiatives/nodeEntry.test.js
@@ -52,14 +52,14 @@ describe("plugins/initiatives/nodeEntry", () => {
 
   describe("normalizeNodeEntry", () => {
     it("should throw without a title", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs: TimestampMs = 123;
       const entry: NodeEntryJson = {key: "no-title"};
       const f = () => normalizeNodeEntry(entry, timestampMs);
       expect(f).toThrow(TypeError);
     });
 
     it("should handle a minimal entry", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs = 123;
       const entry: NodeEntryJson = {title: "Most minimal"};
       const expected: NodeEntry = {
         title: "Most minimal",
@@ -72,7 +72,7 @@ describe("plugins/initiatives/nodeEntry", () => {
     });
 
     it("should handle an entry with weights", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs: TimestampMs = 123;
       const entry: NodeEntryJson = {title: "Include weight", weight: 42};
       const expected: NodeEntry = {
         title: "Include weight",
@@ -85,7 +85,7 @@ describe("plugins/initiatives/nodeEntry", () => {
     });
 
     it("should handle an entry with contributors", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs: TimestampMs = 123;
       const entry: NodeEntryJson = {
         title: "Include contributors",
         contributors: ["https://foo.bar/u/abc"],
@@ -101,7 +101,7 @@ describe("plugins/initiatives/nodeEntry", () => {
     });
 
     it("should handle an entry with timestamp", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs: TimestampMs = 123;
       const entry: NodeEntryJson = {
         title: "Include timestamp",
         timestampIso: Timestamp.toISO(Date.parse("2018-02-03T12:34:56.789Z")),
@@ -110,16 +110,14 @@ describe("plugins/initiatives/nodeEntry", () => {
         title: "Include timestamp",
         key: "include-timestamp",
         contributors: [],
-        timestampMs: Timestamp.fromNumber(
-          Date.parse("2018-02-03T12:34:56.789Z")
-        ),
+        timestampMs: Date.parse("2018-02-03T12:34:56.789Z"),
         weight: null,
       };
       expect(normalizeNodeEntry(entry, timestampMs)).toEqual(expected);
     });
 
     it("should handle an entry with key", () => {
-      const timestampMs: TimestampMs = Timestamp.fromNumber(123);
+      const timestampMs: TimestampMs = 123;
       const entry: NodeEntryJson = {
         title: "Include key",
         key: "much-different-key",
diff --git a/src/util/timestamp.js b/src/util/timestamp.js
index 527492b..963fb48 100644
--- a/src/util/timestamp.js
+++ b/src/util/timestamp.js
@@ -9,7 +9,7 @@
  */
 
 // A timestamp representation in ms since epoch.
-export opaque type TimestampMs: number = number;
+export type TimestampMs = number;
 
 // A timestamp representation in ISO 8601 format.
 export opaque type TimestampISO: string = string;
@@ -22,7 +22,7 @@ export opaque type TimestampISO: string = string;
  * than a forced refactor across the codebase.
  */
 export function toISO(timestampLike: TimestampMs | number): TimestampISO {
-  const timestampMs: TimestampMs = fromNumber(timestampLike);
+  const timestampMs: TimestampMs = validate(timestampLike);
   return new Date(timestampMs).toISOString();
 }
 
@@ -47,13 +47,12 @@ export function fromISO(timestampISO: TimestampISO): TimestampMs {
 }
 
 /**
- * Creates a TimestampMs from a number input.
+ * Validate that a number is potentially a valid timestamp.
  *
- * Since much of the previous types have used `number` as a type instead of
- * TimestampMs. Accepting `number` will give an easier upgrade path, rather
- * than a forced refactor across the codebase.
+ * This checks that the number is a finite integer, which avoids some potential
+ * numbers that are not valid timestamps.
  */
-export function fromNumber(timestampMs: number): TimestampMs {
+export function validate(timestampMs: number): TimestampMs {
   const asNumber = Number(timestampMs);
   if (
     timestampMs === null ||
diff --git a/src/util/timestamp.test.js b/src/util/timestamp.test.js
index edfc7cb..2ac4814 100644
--- a/src/util/timestamp.test.js
+++ b/src/util/timestamp.test.js
@@ -1,7 +1,7 @@
 // @flow
 
 import type {TimestampMs, TimestampISO} from "./timestamp";
-import {fromISO, toISO, fromNumber} from "./timestamp";
+import {fromISO, toISO, validate} from "./timestamp";
 
 /**
  * Helper function to write readable "toThrow" tests. This intentionally
@@ -33,14 +33,14 @@ describe("util/timestamp", () => {
   describe("roundtrips", () => {
     it("should handle number roundtrips", () => {
       const origin: number = fullExample.ms;
-      expect(fromNumber(origin)).toBe(origin);
+      expect(validate(origin)).toBe(origin);
       expect(fromISO(toISO(origin))).toBe(origin);
-      expect(fromNumber(fromISO(toISO(origin)))).toBe(origin);
+      expect(validate(fromISO(toISO(origin)))).toBe(origin);
     });
     it("should handle ISO roundtrips", () => {
       const origin: TimestampISO = fullExample.ISO;
       expect(toISO(fromISO(origin))).toBe(origin);
-      expect(toISO(fromNumber(fromISO(origin)))).toBe(origin);
+      expect(toISO(validate(fromISO(origin)))).toBe(origin);
     });
   });
 
@@ -96,34 +96,34 @@ describe("util/timestamp", () => {
     });
   });
 
-  describe("fromNumber", () => {
+  describe("validate", () => {
     it("should throw on null", () => {
-      given(null).expect(fromNumber).toThrow(TypeError);
+      given(null).expect(validate).toThrow(TypeError);
     });
     it("should throw on undefined", () => {
-      given(undefined).expect(fromNumber).toThrow(TypeError);
+      given(undefined).expect(validate).toThrow(TypeError);
     });
     it("should throw on NaN", () => {
-      given(NaN).expect(fromNumber).toThrow(TypeError);
+      given(NaN).expect(validate).toThrow(TypeError);
     });
     it("should throw on Infinity", () => {
-      given(Infinity).expect(fromNumber).toThrow(TypeError);
+      given(Infinity).expect(validate).toThrow(TypeError);
     });
     it("should throw on floating point numbers", () => {
       given(1 / 3)
-        .expect(fromNumber)
+        .expect(validate)
         .toThrow(TypeError);
     });
     it("should handle 0 correctly", () => {
-      expect(fromNumber(0)).toBe(0);
+      expect(validate(0)).toBe(0);
     });
     it("should handle Date.now correctly", () => {
       const now = Date.now();
-      expect(fromNumber(now)).toBe(now);
+      expect(validate(now)).toBe(now);
     });
     it("should handle examples correctly", () => {
-      expect(fromNumber(fullExample.ms)).toBe(fullExample.ms);
-      expect(fromNumber(partialExample.ms)).toBe(partialExample.ms);
+      expect(validate(fullExample.ms)).toBe(fullExample.ms);
+      expect(validate(partialExample.ms)).toBe(partialExample.ms);
     });
   });
 });