diff --git a/Userland/Applications/Spreadsheet/ExportDialog.cpp b/Userland/Applications/Spreadsheet/ExportDialog.cpp
index 6139060904..37c8f2e72d 100644
--- a/Userland/Applications/Spreadsheet/ExportDialog.cpp
+++ b/Userland/Applications/Spreadsheet/ExportDialog.cpp
@@ -292,7 +292,7 @@ Result<void, String> ExportDialog::make_and_run_for(StringView mime, Core::File&
 
     if (mime == "text/csv") {
         return export_xsv();
-    } else if (mime == "text/plain" && file.filename().ends_with(".sheets")) {
+    } else if (mime == "application/x-sheets+json") {
         return export_worksheet();
     } else {
         auto page = GUI::WizardPage::construct(
diff --git a/Userland/Applications/Spreadsheet/ImportDialog.cpp b/Userland/Applications/Spreadsheet/ImportDialog.cpp
index 50d74c7089..3b5c794f65 100644
--- a/Userland/Applications/Spreadsheet/ImportDialog.cpp
+++ b/Userland/Applications/Spreadsheet/ImportDialog.cpp
@@ -245,7 +245,7 @@ Result<NonnullRefPtrVector<Sheet>, String> ImportDialog::make_and_run_for(GUI::W
 
     if (mime == "text/csv") {
         return import_xsv();
-    } else if (mime == "text/plain" && file.filename().ends_with(".sheets")) {
+    } else if (mime == "application/x-sheets+json") {
         return import_worksheet();
     } else {
         auto page = GUI::WizardPage::construct(