diff --git a/eslint.config.mjs b/eslint.config.mjs
index de32bf1..343a24b 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -16,5 +16,18 @@ export default tseslint.config(
         tsconfigRootDir: import.meta.dirname,
       },
     },
+    rules: {
+      "no-shadow": "off",
+      "@typescript-eslint/no-shadow": "error",
+      "@typescript-eslint/strict-boolean-expressions": [
+        "error",
+        {
+          allowString: true,
+          allowNumber: false,
+          allowNullableObject: false,
+        },
+      ],
+      "@typescript-eslint/switch-exhaustiveness-check": "error",
+    },
   },
 );
diff --git a/src/publish.ts b/src/publish.ts
index 6caec36..b9ae812 100644
--- a/src/publish.ts
+++ b/src/publish.ts
@@ -23,7 +23,7 @@ function checkRequestAuthentication(
   expectedPassword: Buffer,
 ): Response | "ok" {
   const authorization = request.headers.get("Authorization");
-  if (!authorization) {
+  if (authorization === null) {
     return new Response("Authorization failed", {
       status: 401, // Unauthorized
       headers: {
@@ -240,14 +240,14 @@ export async function handlePublish(
     }
 
     if (key.endsWith(".minisign")) {
-      assert(!artifactMinisigns[key]); // keys are unique
+      assert(artifactMinisigns[key] === undefined); // keys are unique
       artifactMinisigns[key] = file;
       continue;
     }
 
     const match = key.match(artifactRegex);
 
-    if (!match) {
+    if (match === null) {
       return new Response(`failed to parse artifact '${key}'!`, {
         status: 400, // Bad Request
       });
@@ -264,7 +264,7 @@ export async function handlePublish(
     //   `os=${os}, arch=${arch}, version=${version}, extension=${extension}, shasum=${file_hash.digest("hex")}, size=${value.size.toString()}`,
     // );
 
-    if (!SemanticVersion.parse(version)) {
+    if (SemanticVersion.parse(version) === null) {
       return new Response(
         `artifact '${key}' has an invalid version '${version}'!`,
         {
diff --git a/src/select-zls-version.ts b/src/select-zls-version.ts
index 45ec3a0..ec3df03 100644
--- a/src/select-zls-version.ts
+++ b/src/select-zls-version.ts
@@ -92,7 +92,7 @@ export async function handleSelectZLSVersion(
 
   const zigVersion = SemanticVersion.parse(zigVersionString);
 
-  if (!zigVersion) {
+  if (zigVersion === null) {
     return new Response(
       `Query component 'zig_version' with value '${zigVersionString}' is not a valid version!`,
       {
@@ -139,7 +139,7 @@ async function selectOnTaggedRelease(
     .bind(zigVersion.major, zigVersion.minor)
     .first<{ JsonData: string }>();
 
-  if (!selectedRelease) return null;
+  if (selectedRelease === null) return null;
   return JSON.parse(selectedRelease.JsonData) as D2JsonData;
 }
 
@@ -221,7 +221,7 @@ async function selectOnDevelopmentBuild(
     .bind(zigVersion.major, zigVersion.minor)
     .all<{ JsonData: string }>();
 
-  if (!releases.results.length) return null;
+  if (releases.results.length === 0) return null;
 
   const oldestRelease = releases.results[0];
   const oldestReleaseData = JSON.parse(oldestRelease.JsonData) as D2JsonData;
diff --git a/src/semantic-version.ts b/src/semantic-version.ts
index 55026ae..2ff010f 100644
--- a/src/semantic-version.ts
+++ b/src/semantic-version.ts
@@ -22,7 +22,7 @@ export class SemanticVersion {
     const regex =
       /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-dev\.(\d+)\+([0-9a-fA-F]{7,9}))?$/;
     const match = string.match(regex);
-    if (!match) return null;
+    if (match === null) return null;
 
     const semver = new SemanticVersion();
     semver.major = parseInt(match[1]);
@@ -71,7 +71,7 @@ export class SemanticVersion {
   public toString(): string {
     const a = `${this.major.toString()}.${this.minor.toString()}.${this.patch.toString()}`;
     if (this.isRelease) return a;
-    assert(this.commitHeight && this.commitID);
+    assert(this.commitHeight !== undefined && this.commitID !== undefined);
     return `${a}-dev.${this.commitHeight.toString()}+${this.commitID}`;
   }
 
diff --git a/test/publish.test.ts b/test/publish.test.ts
index 860af1c..c46125f 100644
--- a/test/publish.test.ts
+++ b/test/publish.test.ts
@@ -18,7 +18,7 @@ async function searchZLSRelease(
   )
     .bind(zlsVersion)
     .first<string>("JsonData");
-  if (!jsonString) return null;
+  if (jsonString === null) return null;
   return JSON.parse(jsonString) as D2JsonData;
 }