diff --git a/src/quest_editor/scripting/AssemblyAnalyser.ts b/src/quest_editor/scripting/AssemblyAnalyser.ts
index 1f6f7d36..09f73854 100644
--- a/src/quest_editor/scripting/AssemblyAnalyser.ts
+++ b/src/quest_editor/scripting/AssemblyAnalyser.ts
@@ -4,6 +4,7 @@ import {
     AssemblyChangeInput,
     AssemblySettingsChangeInput,
     AssemblyWorkerOutput,
+    DefinitionInput,
     InputMessageType,
     NewAssemblyInput,
     OutputMessageType,
@@ -23,6 +24,7 @@ import CompletionItem = languages.CompletionItem;
 import IModelContentChange = editor.IModelContentChange;
 import SignatureHelp = languages.SignatureHelp;
 import ParameterInformation = languages.ParameterInformation;
+import LocationLink = languages.LocationLink;
 
 const INSTRUCTION_SUGGESTIONS = OPCODES.filter(opcode => opcode != null).map(opcode => {
     return ({
@@ -111,24 +113,27 @@ export class AssemblyAnalyser implements Disposable {
     }
 
     async provide_signature_help(line_no: number, col: number): Promise<SignatureHelp | undefined> {
-        const id = this.message_id++;
-
-        return new Promise<SignatureHelp>((resolve, reject) => {
-            this.promises.set(id, { resolve, reject });
-            const message: SignatureHelpInput = {
+        return await this.send_and_await_response<SignatureHelpInput, SignatureHelp>(
+            "Signature help provision",
+            id => ({
                 type: InputMessageType.SignatureHelp,
                 id,
                 line_no,
                 col,
-            };
-            this.worker.postMessage(message);
+            }),
+        );
+    }
 
-            setTimeout(() => {
-                if (this.promises.delete(id)) {
-                    reject(new Error("Signature help timed out."));
-                }
-            }, 5_000);
-        });
+    async provide_definition(line_no: number, col: number): Promise<LocationLink[]> {
+        return await this.send_and_await_response<DefinitionInput, LocationLink[]>(
+            "Definition provision",
+            id => ({
+                type: InputMessageType.Definition,
+                id,
+                line_no,
+                col,
+            }),
+        );
     }
 
     update_settings(changed_settings: Partial<AssemblySettings>): void {
@@ -143,6 +148,25 @@ export class AssemblyAnalyser implements Disposable {
         this.worker.terminate();
     }
 
+    private async send_and_await_response<M, R>(
+        name: string,
+        create_request: (id: number) => M,
+    ): Promise<R> {
+        const id = this.message_id++;
+
+        return new Promise<R>((resolve, reject) => {
+            this.promises.set(id, { resolve, reject });
+            const message: M = create_request(id);
+            this.worker.postMessage(message);
+
+            setTimeout(() => {
+                if (this.promises.delete(id)) {
+                    reject(new Error(`${name} timed out.`));
+                }
+            }, 5_000);
+        });
+    }
+
     private process_worker_message = (e: MessageEvent): void => {
         const message: AssemblyWorkerOutput = e.data;
 
@@ -158,6 +182,7 @@ export class AssemblyAnalyser implements Disposable {
                     this._issues.val = { warnings: message.warnings, errors: message.errors };
                 }
                 break;
+
             case OutputMessageType.SignatureHelp:
                 {
                     const promise = this.promises.get(message.id);
@@ -230,6 +255,18 @@ export class AssemblyAnalyser implements Disposable {
                     }
                 }
                 break;
+
+            case OutputMessageType.Definition:
+                {
+                    const promise = this.promises.get(message.id);
+
+                    if (promise) {
+                        this.promises.delete(message.id);
+                        // TODO: resolve LocationLinks
+                        promise.resolve([]);
+                    }
+                }
+                break;
         }
     };
 }
diff --git a/src/quest_editor/scripting/assembly_worker.ts b/src/quest_editor/scripting/assembly_worker.ts
index 2428e94f..49fd1ab1 100644
--- a/src/quest_editor/scripting/assembly_worker.ts
+++ b/src/quest_editor/scripting/assembly_worker.ts
@@ -2,6 +2,8 @@ import {
     AssemblyChangeInput,
     AssemblySettingsChangeInput,
     AssemblyWorkerInput,
+    DefinitionInput,
+    DefinitionOutput,
     InputMessageType,
     NewObjectCodeOutput,
     OutputMessageType,
@@ -57,6 +59,9 @@ function process_messages(): void {
             case InputMessageType.SignatureHelp:
                 signature_help(message);
                 break;
+            case InputMessageType.Definition:
+                definition(message);
+                break;
             case InputMessageType.SettingsChange:
                 settings_change(message);
                 break;
@@ -138,6 +143,15 @@ function signature_help(message: SignatureHelpInput): void {
     ctx.postMessage(response);
 }
 
+function definition(message: DefinitionInput): void {
+    // TODO: provide definition
+    const response: DefinitionOutput = {
+        type: OutputMessageType.Definition,
+        id: message.id,
+    };
+    ctx.postMessage(response);
+}
+
 /**
  * Apply changes to settings.
  */
diff --git a/src/quest_editor/scripting/assembly_worker_messages.ts b/src/quest_editor/scripting/assembly_worker_messages.ts
index bb6936dd..04ed52f9 100644
--- a/src/quest_editor/scripting/assembly_worker_messages.ts
+++ b/src/quest_editor/scripting/assembly_worker_messages.ts
@@ -6,6 +6,7 @@ export enum InputMessageType {
     NewAssembly,
     AssemblyChange,
     SignatureHelp,
+    Definition,
     SettingsChange,
 }
 
@@ -13,6 +14,7 @@ export type AssemblyWorkerInput =
     | NewAssemblyInput
     | AssemblyChangeInput
     | SignatureHelpInput
+    | DefinitionInput
     | AssemblySettingsChangeInput;
 
 export type NewAssemblyInput = {
@@ -38,6 +40,13 @@ export type SignatureHelpInput = {
     readonly col: number;
 };
 
+export type DefinitionInput = {
+    readonly type: InputMessageType.Definition;
+    readonly id: number;
+    readonly line_no: number;
+    readonly col: number;
+};
+
 export type AssemblySettingsChangeInput = {
     readonly type: InputMessageType.SettingsChange;
     readonly settings: Partial<AssemblySettings>;
@@ -46,9 +55,10 @@ export type AssemblySettingsChangeInput = {
 export enum OutputMessageType {
     NewObjectCode,
     SignatureHelp,
+    Definition,
 }
 
-export type AssemblyWorkerOutput = NewObjectCodeOutput | SignatureHelpOutput;
+export type AssemblyWorkerOutput = NewObjectCodeOutput | SignatureHelpOutput | DefinitionOutput;
 
 export type NewObjectCodeOutput = {
     readonly type: OutputMessageType.NewObjectCode;
@@ -64,3 +74,8 @@ export type SignatureHelpOutput = {
     readonly opcode?: Opcode;
     readonly active_param: number;
 };
+
+export type DefinitionOutput = {
+    readonly type: OutputMessageType.Definition;
+    readonly id: number;
+};
diff --git a/src/quest_editor/stores/AsmEditorStore.ts b/src/quest_editor/stores/AsmEditorStore.ts
index 60b51dda..8643196b 100644
--- a/src/quest_editor/stores/AsmEditorStore.ts
+++ b/src/quest_editor/stores/AsmEditorStore.ts
@@ -14,6 +14,7 @@ import ITextModel = editor.ITextModel;
 import CompletionList = languages.CompletionList;
 import IMarkerData = editor.IMarkerData;
 import SignatureHelpResult = languages.SignatureHelpResult;
+import LocationLink = languages.LocationLink;
 
 const assembly_analyser = new AssemblyAnalyser();
 
@@ -69,6 +70,12 @@ languages.setLanguageConfiguration("psoasm", {
     },
 });
 
+languages.registerDefinitionProvider("psoasm", {
+    provideDefinition(_model: ITextModel, position: Position): Promise<LocationLink[]> {
+        return assembly_analyser.provide_definition(position.lineNumber, position.column);
+    },
+});
+
 export class AsmEditorStore implements Disposable {
     private readonly disposer = new Disposer();
     private readonly model_disposer = this.disposer.add(new Disposer());