diff --git a/src/modifyQuery.ts b/src/modifyQuery.ts
index 495fc42..8bd58b4 100644
--- a/src/modifyQuery.ts
+++ b/src/modifyQuery.ts
@@ -40,5 +40,5 @@ export function addAddHocFilter(query: string, filter: AdHocVariableFilter): str
       addHocFilter = `${key}:<${value}`;
       break;
   }
-  return concatenate(query, addHocFilter);
+  return concatenate(query, addHocFilter,'AND');
 }
diff --git a/src/utils/lucene.ts b/src/utils/lucene.ts
index 99e0275..0fd9c52 100644
--- a/src/utils/lucene.ts
+++ b/src/utils/lucene.ts
@@ -198,7 +198,7 @@ export class LuceneQuery {
     value = escapeFilterValue(value);
     const filter = `${modifier}${key}:"${value}"`;
 
-    return LuceneQuery.parse(concatenate(this.toString(), filter));
+    return LuceneQuery.parse(concatenate(this.toString(), filter,'AND'));
   }
 
   removeFilter(key: string, value: string, modifier: ModifierType = ''){