diff --git a/src/calibre/gui2/store/stores/diesel_ebooks_plugin.py b/src/calibre/gui2/store/stores/diesel_ebooks_plugin.py
index 1d410e2c38..3991be554d 100644
--- a/src/calibre/gui2/store/stores/diesel_ebooks_plugin.py
+++ b/src/calibre/gui2/store/stores/diesel_ebooks_plugin.py
@@ -72,7 +72,7 @@ class DieselEbooksStore(BasicStoreConfig, StorePlugin):
                 formats = ', '.join(data.xpath('.//div[@class="book-info"]//text()')).strip()
                 a, b, formats = formats.partition('Format:')
                 drm = SearchResult.DRM_LOCKED
-                if 'drm free' not in formats.lower():
+                if 'drm free' in formats.lower():
                     drm = SearchResult.DRM_UNLOCKED