diff --git a/package.json b/package.json
index 8920a7e..1c97ca9 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "partial-diff",
   "displayName": "Partial Diff",
   "description": "Compare (diff) text selections within a file, across files, or to the clipboard",
-  "version": "1.4.3",
+  "version": "1.4.4",
   "publisher": "ryu1kn",
   "license": "SEE LICENSE IN LICENSE.txt",
   "icon": "images/partial-diff_128x128.png",
diff --git a/src/lib/diff-presenter.ts b/src/lib/diff-presenter.ts
index 2ec188f..7ff2be0 100644
--- a/src/lib/diff-presenter.ts
+++ b/src/lib/diff-presenter.ts
@@ -7,7 +7,7 @@ import DiffTitleBuilder from './diff-title-builder';
 export default class DiffPresenter {
     private readonly diffTitleBuilder: DiffTitleBuilder;
 
-    constructor(selectionInfoRegistry: SelectionInfoRegistry,
+    constructor(private readonly selectionInfoRegistry: SelectionInfoRegistry,
                 normalisationRuleStore: NormalisationRuleStore,
                 private readonly commandAdaptor: CommandAdaptor,
                 private readonly getCurrentDate: () => Date) {
@@ -17,7 +17,8 @@ export default class DiffPresenter {
     }
 
     takeDiff(textKey1: string, textKey2: string): Promise<{} | undefined> {
-        const getUri = (textKey: string) => makeUriString(textKey, this.getCurrentDate());
+        const getFileName = (textKey: string) => this.selectionInfoRegistry.get(textKey).fileName;
+        const getUri = (textKey: string) => makeUriString(textKey, getFileName(textKey), this.getCurrentDate());
         const title = this.diffTitleBuilder.build(textKey1, textKey2);
         return this.commandAdaptor.executeCommand('vscode.diff', getUri(textKey1), getUri(textKey2), title);
     }
diff --git a/src/lib/utils/text-resource.ts b/src/lib/utils/text-resource.ts
index 3146b75..ee4a8c7 100644
--- a/src/lib/utils/text-resource.ts
+++ b/src/lib/utils/text-resource.ts
@@ -1,8 +1,9 @@
+import {URLSearchParams} from 'url';
 import * as vscode from 'vscode';
 import {EXTENSION_SCHEME} from '../const';
 
-export const makeUriString = (textKey: string, timestamp: Date): string =>
-    `${EXTENSION_SCHEME}:text/${textKey}?_ts=${timestamp.getTime()}`; // `_ts` to avoid cache
+export const makeUriString = (textKey: string, fileName: string, timestamp: Date): string =>
+    `${EXTENSION_SCHEME}:text/${fileName}?key=${textKey}&_ts=${timestamp.getTime()}`; // `_ts` to avoid cache
 
 export const extractTextKey = (uri: vscode.Uri): string =>
-    uri.path.match(/^text\/([a-z\d]+)/)![1];
+    new URLSearchParams(uri.query).get('key')!;
diff --git a/src/test/lib/commands/compare-selection-with-clipboard.test.ts b/src/test/lib/commands/compare-selection-with-clipboard.test.ts
index 4a36d16..544f498 100644
--- a/src/test/lib/commands/compare-selection-with-clipboard.test.ts
+++ b/src/test/lib/commands/compare-selection-with-clipboard.test.ts
@@ -42,8 +42,8 @@ suite('CompareSelectionWithClipboardCommand', () => {
         });
         verify(commandAdaptor.executeCommand(
             'vscode.diff',
-            'partialdiff:text/clipboard?_ts=1465990980000',
-            'partialdiff:text/reg2?_ts=1465990980000',
+            'partialdiff:text/Clipboard?key=clipboard&_ts=1465990980000',
+            'partialdiff:text/FILE2?key=reg2&_ts=1465990980000',
             'Clipboard ↔ FILE2 (ll.6-11)'
         ));
     });
diff --git a/src/test/lib/commands/compare-selection-with-text1.test.ts b/src/test/lib/commands/compare-selection-with-text1.test.ts
index e1b0547..e53f783 100644
--- a/src/test/lib/commands/compare-selection-with-text1.test.ts
+++ b/src/test/lib/commands/compare-selection-with-text1.test.ts
@@ -42,8 +42,8 @@ suite('CompareSelectionWithText1', () => {
         });
         verify(commandAdaptor.executeCommand(
             'vscode.diff',
-            'partialdiff:text/reg1?_ts=1465990980000',
-            'partialdiff:text/reg2?_ts=1465990980000',
+            'partialdiff:text/FILE1?key=reg1&_ts=1465990980000',
+            'partialdiff:text/FILE2?key=reg2&_ts=1465990980000',
             'FILE1 (ll.21-26) ↔ FILE2 (ll.6-11)'
         ));
     });
diff --git a/src/test/lib/commands/compare-visible-editors.test.ts b/src/test/lib/commands/compare-visible-editors.test.ts
index df5a074..45058bf 100644
--- a/src/test/lib/commands/compare-visible-editors.test.ts
+++ b/src/test/lib/commands/compare-visible-editors.test.ts
@@ -38,8 +38,8 @@ suite('CompareVisibleEditorsCommand', () => {
         });
         verify(deps.commandAdaptor.executeCommand(
             'vscode.diff',
-            'partialdiff:text/visible1?_ts=1465990980000',
-            'partialdiff:text/visible2?_ts=1465990980000',
+            'partialdiff:text/FILE1?key=visible1&_ts=1465990980000',
+            'partialdiff:text/FILE2?key=visible2&_ts=1465990980000',
             'FILE1 (ll.6-11) ↔ FILE2 (ll.16-21)'
         ));
     });
diff --git a/src/test/lib/content-provider.test.ts b/src/test/lib/content-provider.test.ts
index 23551b2..8a8815c 100644
--- a/src/test/lib/content-provider.test.ts
+++ b/src/test/lib/content-provider.test.ts
@@ -21,12 +21,12 @@ suite('ContentProvider', () => {
         const contentProvider = new ContentProvider(selectionInfoRegistry, normalisationRuleStore);
 
         test('it extracts text key from the given uri and uses it to retrieve text', () => {
-            const uri = mockType<vscode.Uri>({path: 'text/key1'});
+            const uri = mockType<vscode.Uri>({path: 'text/file.txt', query: 'key=key1'});
             assert.deepEqual(contentProvider.provideTextDocumentContent(uri), 'TEXT:1');
         });
 
         test('it returns an empty string if a text is not yet selected', () => {
-            const uri = mockType<vscode.Uri>({path: 'text/keyNotExist'});
+            const uri = mockType<vscode.Uri>({path: 'text/file.txt', query: 'key=keyNotExist'});
             assert.deepEqual(contentProvider.provideTextDocumentContent(uri), '');
         });
     });
@@ -36,7 +36,7 @@ suite('ContentProvider', () => {
         const contentProvider = new ContentProvider(selectionInfoRegistry, normalisationRuleStore);
 
         test('it returns the registered text as is', () => {
-            const uri = mockType<vscode.Uri>({path: 'text/key1'});
+            const uri = mockType<vscode.Uri>({path: 'text/file.txt', query: 'key=key1'});
             assert.deepEqual(contentProvider.provideTextDocumentContent(uri), 'TEXT_1');
         });
     });
diff --git a/src/test/lib/diff-presenter.test.ts b/src/test/lib/diff-presenter.test.ts
index d211e3b..b9b2f95 100644
--- a/src/test/lib/diff-presenter.test.ts
+++ b/src/test/lib/diff-presenter.test.ts
@@ -23,8 +23,8 @@ suite('DiffPresenter', () => {
 
         verify(commandAdaptor.executeCommand(
             'vscode.diff',
-            'partialdiff:text/TEXT1?_ts=1465990980000',
-            'partialdiff:text/TEXT2?_ts=1465990980000',
+            'partialdiff:text/FILE1?key=TEXT1&_ts=1465990980000',
+            'partialdiff:text/FILE2?key=TEXT2&_ts=1465990980000',
             'FILE1 \u2194 FILE2'
         ));
     });
diff --git a/src/test/lib/text-resource-util.test.ts b/src/test/lib/text-resource-util.test.ts
index e6e8d93..33816e7 100644
--- a/src/test/lib/text-resource-util.test.ts
+++ b/src/test/lib/text-resource-util.test.ts
@@ -1,19 +1,19 @@
 import {extractTextKey, makeUriString} from '../../lib/utils/text-resource';
 import * as assert from 'assert';
-import {Uri} from 'vscode';
+import type {Uri} from 'vscode';
 
 suite('Text Resource Utilities', () => {
     const date = new Date('2016-06-15T11:43:00Z');
 
     suite('#makeUriString', () => {
         test('it converts a given text key into an uri', () => {
-            assert.deepEqual(makeUriString('reg1', date), 'partialdiff:text/reg1?_ts=1465990980000');
+            assert.deepEqual(makeUriString('reg1', 'file.txt', date), 'partialdiff:text/file.txt?key=reg1&_ts=1465990980000');
         });
     });
 
     suite('#extractTextKey', () => {
         test('it extracts a text key information from the given uri', () => {
-            const uri = {path: 'text/reg1'};
+            const uri = {path: 'text/file.txt', query: 'key=reg1'};
             assert.deepEqual(extractTextKey(uri as Uri), 'reg1');
         });
     });