diff --git a/src/datasource/load_data.spec.ts b/src/datasource/load_data.spec.ts
index 48b60c1..cb65607 100644
--- a/src/datasource/load_data.spec.ts
+++ b/src/datasource/load_data.spec.ts
@@ -7,7 +7,7 @@ describe('loadFile', () => {
 
   it('loads GEDCOM file', async () => {
     const file = readFileSync('src/datasource/testdata/test.ged');
-    const blob = new Blob([file]);
+    const blob = new Blob([file]) as globalThis.Blob;
     const {gedcom, images} = await loadFile(blob);
     expect(gedcom.length).toBe(4408);
     expect(images).toEqual(new Map());
@@ -15,7 +15,7 @@ describe('loadFile', () => {
 
   it('loads GEDZIP file', async () => {
     const file = readFileSync('src/datasource/testdata/test.gdz');
-    const blob = new Blob([file]);
+    const blob = new Blob([file]) as globalThis.Blob;
     const {gedcom, images} = await loadFile(blob);
     expect(gedcom.length).toBe(4408);
     expect(images.size).toBe(1);