diff --git a/ghost/core/test/e2e-api/admin/images.test.js b/ghost/core/test/e2e-api/admin/images.test.js
index ee882b35cb..8d4aad72ea 100644
--- a/ghost/core/test/e2e-api/admin/images.test.js
+++ b/ghost/core/test/e2e-api/admin/images.test.js
@@ -342,7 +342,7 @@ describe('Images API', function () {
         const brokenPayload = '--boundary\r\nContent-Disposition: form-data; name=\"image\"; filename=\"example.png\"\r\nContent-Type: image/png\r\n\r\n';
 
         // eslint-disable-next-line no-undef
-        const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, blob.size / 2)], {
+        const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, Math.floor(blob.size / 2))], {
             type: 'multipart/form-data; boundary=boundary'
         })).text();
 
@@ -367,7 +367,7 @@ describe('Images API', function () {
         const brokenPayload = '--boundary\r\nContent-Disposition: form-data; name=\"image\"; filename=\"example.png\"\r\nContent-Type: image/png\r\n';
 
         // eslint-disable-next-line no-undef
-        const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, blob.size / 2)], {
+        const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, Math.floor(blob.size / 2))], {
             type: 'multipart/form-data; boundary=boundary'
         })).text();
 
diff --git a/ghost/core/test/e2e-api/admin/media.test.js b/ghost/core/test/e2e-api/admin/media.test.js
index 0baaef3e5a..5f88cb489e 100644
--- a/ghost/core/test/e2e-api/admin/media.test.js
+++ b/ghost/core/test/e2e-api/admin/media.test.js
@@ -140,7 +140,7 @@ describe('Media API', function () {
             const brokenPayload = '--boundary\r\nContent-Disposition: form-data; name=\"image\"; filename=\"example.png\"\r\nContent-Type: image/png\r\n\r\n';
 
             // eslint-disable-next-line no-undef
-            const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, blob.size / 2)], {
+            const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, Math.floor(blob.size / 2))], {
                 type: 'multipart/form-data; boundary=boundary'
             })).text();
 
@@ -164,7 +164,7 @@ describe('Media API', function () {
             const brokenPayload = '--boundary\r\nContent-Disposition: form-data; name=\"image\"; filename=\"example.png\"\r\nContent-Type: image/png\r\n';
 
             // eslint-disable-next-line no-undef
-            const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, blob.size / 2)], {
+            const brokenDataBlob = await (new Blob([brokenPayload, blob.slice(0, Math.floor(blob.size / 2))], {
                 type: 'multipart/form-data; boundary=boundary'
             })).text();