diff --git a/language-server/src/features/deprecated.js b/language-server/src/features/deprecated.js
index bdd05f9..9accc0b 100644
--- a/language-server/src/features/deprecated.js
+++ b/language-server/src/features/deprecated.js
@@ -1,16 +1,18 @@
 import { DiagnosticSeverity, DiagnosticTag } from "vscode-languageserver";
 import * as SchemaNode from "../schema-node.js";
-import { subscribe } from "../pubsub.js";
+import { subscribe, unsubscribe } from "../pubsub.js";
 
 /** @import { Feature } from "../build-server.js" */
 
 
 const annotationDialectUri = "https://json-schema.org/draft/2020-12/schema";
+/** @type string */
+let subscriptionToken;
 
 /** @type Feature */
 export default {
   load() {
-    subscribe("diagnostics", async (_message, { schemaDocument, diagnostics }) => {
+    subscriptionToken = subscribe("diagnostics", async (_message, { schemaDocument, diagnostics }) => {
       for (const schemaResource of schemaDocument.schemaResources) {
         for (const deprecated of SchemaNode.annotatedWith(schemaResource, "deprecated", annotationDialectUri)) {
           if (SchemaNode.annotation(deprecated, "deprecated", annotationDialectUri).some((deprecated) => deprecated)) {
@@ -34,5 +36,6 @@ export default {
   },
 
   onShutdown() {
+    unsubscribe("diagnostics", subscriptionToken);
   }
 };
diff --git a/language-server/src/features/if-then-completion.js b/language-server/src/features/if-then-completion.js
index 0dd07b2..42fee82 100644
--- a/language-server/src/features/if-then-completion.js
+++ b/language-server/src/features/if-then-completion.js
@@ -1,14 +1,16 @@
 import { CompletionItemKind, InsertTextFormat } from "vscode-languageserver";
 import * as SchemaDocument from "../schema-document.js";
-import { subscribe } from "../pubsub.js";
+import { subscribe, unsubscribe } from "../pubsub.js";
 
 /** @import { Feature } from "../build-server.js" */
 
+/** @type string */
+let subscriptionToken;
 
 /** @type Feature */
 export default {
   load() {
-    subscribe("completions", async (_message, { schemaDocument, offset, completions }) => {
+    subscriptionToken = subscribe("completions", async (_message, { schemaDocument, offset, completions }) => {
       const currentProperty = SchemaDocument.findNodeAtOffset(schemaDocument, offset);
       if (currentProperty && currentProperty.pointer.endsWith("/if") && currentProperty.type === "property") {
         completions.push(...ifThenPatternCompletion);
@@ -24,6 +26,7 @@ export default {
   },
 
   onShutdown() {
+    unsubscribe("completions", subscriptionToken);
   }
 };
 
diff --git a/language-server/src/features/schema-completion.js b/language-server/src/features/schema-completion.js
index f9e122c..7e5b330 100644
--- a/language-server/src/features/schema-completion.js
+++ b/language-server/src/features/schema-completion.js
@@ -1,10 +1,12 @@
 import { CompletionItemKind } from "vscode-languageserver";
 import { getDialectIds } from "@hyperjump/json-schema/experimental";
 import * as SchemaDocument from "../schema-document.js";
-import { subscribe } from "../pubsub.js";
+import { subscribe, unsubscribe } from "../pubsub.js";
 
 /** @import { Feature } from "../build-server.js"; */
 
+/** @type string */
+let subscriptionToken;
 
 /** @type Feature */
 export default {
@@ -16,7 +18,7 @@ export default {
     ]);
     const shouldHaveTrailingHash = (/** @type string */ uri) => trailingHashDialects.has(uri);
 
-    subscribe("completions", async (_message, { schemaDocument, offset, completions }) => {
+    subscriptionToken = subscribe("completions", async (_message, { schemaDocument, offset, completions }) => {
       const currentProperty = SchemaDocument.findNodeAtOffset(schemaDocument, offset);
       if (currentProperty && currentProperty.pointer.endsWith("/$schema") && currentProperty.type === "string") {
         completions.push(...getDialectIds().map((uri) => ({
@@ -35,5 +37,6 @@ export default {
   },
 
   onShutdown() {
+    unsubscribe("completions", subscriptionToken);
   }
 };
diff --git a/language-server/src/features/validate-references.js b/language-server/src/features/validate-references.js
index b5132e1..ba3c3e1 100644
--- a/language-server/src/features/validate-references.js
+++ b/language-server/src/features/validate-references.js
@@ -1,5 +1,5 @@
 import * as SchemaNode from "../schema-node.js";
-import { subscribe } from "../pubsub.js";
+import { subscribe, unsubscribe } from "../pubsub.js";
 import { keywordNameFor } from "../util.js";
 
 /**
@@ -8,10 +8,13 @@ import { keywordNameFor } from "../util.js";
  */
 
 
+/** @type string */
+let subscriptionToken;
+
 /** @type Feature */
 export default {
   load() {
-    subscribe("diagnostics", async (_message, { schemaDocument, diagnostics }) => {
+    subscriptionToken = subscribe("diagnostics", async (_message, { schemaDocument, diagnostics }) => {
       for (const schemaResource of schemaDocument.schemaResources) {
         for (const node of references(schemaResource)) {
           const reference = SchemaNode.value(node);
@@ -32,6 +35,7 @@ export default {
   },
 
   onShutdown() {
+    unsubscribe("diagnostics", subscriptionToken);
   }
 };