diff --git a/web/src/lib/stores/trail_store.ts b/web/src/lib/stores/trail_store.ts
index b05de3ac..d8173983 100644
--- a/web/src/lib/stores/trail_store.ts
+++ b/web/src/lib/stores/trail_store.ts
@@ -584,7 +584,8 @@ function buildFilterText(user: AuthRecord, filter: TrailFilter, includeGeo: bool
     }
 
     if (filter.category.length > 0) {
-        filterText += ` AND category IN ['${filter.category.join(",")}']`;
+        const categoryValues = filter.category.map(category => `'${category}'`).join(", ");
+        filterText += ` AND category IN [${categoryValues}]`;
     }
 
     if (filter.tags.length > 0) {