diff --git a/.eslintrc.js b/.eslintrc.js
index 132caa6..bd5a90a 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -21,6 +21,7 @@ module.exports = {
     "plugin:flowtype/recommended",
   ],
   rules: {
+    "prefer-const": ["warn"],
     camelcase: ["error", {properties: "never", allow: ["^_unused_.*"]}],
     eqeqeq: ["error", "always", {null: "ignore"}],
     "no-unused-vars": [
diff --git a/src/core/algorithm/markovChain.js b/src/core/algorithm/markovChain.js
index c868b73..54d2722 100644
--- a/src/core/algorithm/markovChain.js
+++ b/src/core/algorithm/markovChain.js
@@ -203,7 +203,7 @@ export function findStationaryDistribution(
   params: PagerankParams,
   options: PagerankOptions
 ): Promise<StationaryDistributionResult> {
-  let gen = findStationaryDistributionGenerator(params, {
+  const gen = findStationaryDistributionGenerator(params, {
     verbose: options.verbose,
     convergenceThreshold: options.convergenceThreshold,
     maxIterations: options.maxIterations,
diff --git a/src/explorer/legacy/pagerankTable/Table.test.js b/src/explorer/legacy/pagerankTable/Table.test.js
index 483e618..fb405dd 100644
--- a/src/explorer/legacy/pagerankTable/Table.test.js
+++ b/src/explorer/legacy/pagerankTable/Table.test.js
@@ -84,7 +84,7 @@ describe("explorer/legacy/pagerankTable/Table", () => {
         const {element} = await setup();
         findButton(element).simulate("click");
         findButton(element).simulate("click");
-        let button = findButton(element);
+        const button = findButton(element);
         expect(button.text()).toEqual("Show weight configuration");
         expect(element.find({"data-test-weight-config": true})).toHaveLength(0);
       });
diff --git a/src/plugins/git/edges.js b/src/plugins/git/edges.js
index fd2a5ab..63849b1 100644
--- a/src/plugins/git/edges.js
+++ b/src/plugins/git/edges.js
@@ -75,7 +75,7 @@ function lengthDecode(
 }
 function multiLengthDecode(x: $ReadOnlyArray<string>, fail: () => Error) {
   let remaining = x;
-  let partses = [];
+  const partses = [];
   while (remaining.length > 0) {
     const {parts, rest} = lengthDecode(remaining, fail);
     partses.push(parts);
diff --git a/src/plugins/github/edges.js b/src/plugins/github/edges.js
index 6d47b4c..c0a1e13 100644
--- a/src/plugins/github/edges.js
+++ b/src/plugins/github/edges.js
@@ -177,7 +177,7 @@ function lengthDecode(
 }
 function multiLengthDecode(x: $ReadOnlyArray<string>, fail: () => Error) {
   let remaining = x;
-  let partses = [];
+  const partses = [];
   while (remaining.length > 0) {
     const {parts, rest} = lengthDecode(remaining, fail);
     partses.push(parts);
diff --git a/src/plugins/github/relationalView.test.js b/src/plugins/github/relationalView.test.js
index 24bc2b7..f78d726 100644
--- a/src/plugins/github/relationalView.test.js
+++ b/src/plugins/github/relationalView.test.js
@@ -299,7 +299,7 @@ describe("plugins/github/relationalView", () => {
       }
       function commitChain(n: number): T.Commit[] {
         let head = wrapCommit(0, []);
-        let results = [head];
+        const results = [head];
         for (let i = 1; i < n; i++) {
           head = wrapCommit(i, [head]);
           results.push(head);
@@ -307,7 +307,7 @@ describe("plugins/github/relationalView", () => {
         return results;
       }
       const commits = commitChain(COMMIT_CHAIN_LENGTH);
-      let pullRequests: T.PullRequest[] = [];
+      const pullRequests: T.PullRequest[] = [];
       function pullRequest(
         prNumber: number,
         mergeCommit: T.Commit