diff --git a/src/engine/transaction.cpp b/src/engine/transaction.cpp
--- a/src/engine/transaction.cpp
+++ b/src/engine/transaction.cpp
@@ -325,7 +325,18 @@
 
     const auto subQueries = query.subQueries();
     for (const EngineQuery& q : subQueries) {
-        vec << postingIterator(q);
+        auto iterator = postingIterator(q);
+        if (iterator) {
+            vec << iterator;
+        } else if (query.op() == EngineQuery::And) {
+            return nullptr;
+        }
+    }
+
+    if (vec.empty()) {
+        return nullptr;
+    } else if (vec.size() == 1) {
+        return vec.takeFirst();
     }
 
     if (query.op() == EngineQuery::And) {
diff --git a/src/lib/searchstore.cpp b/src/lib/searchstore.cpp
--- a/src/lib/searchstore.cpp
+++ b/src/lib/searchstore.cpp
@@ -165,11 +165,19 @@
         vec.reserve(subTerms.size());
 
         for (const Term& t : subTerms) {
-            vec << constructQuery(tr, t);
+            auto iterator = constructQuery(tr, t);
+            // constructQuery returns a nullptr to signal an empty list
+            if (iterator) {
+                vec << iterator;
+            } else if (term.operation() == Term::And) {
+                return nullptr;
+            }
         }
 
         if (vec.isEmpty()) {
             return nullptr;
+        } else if (vec.size() == 1) {
+            return vec.takeFirst();
         }
 
         if (term.operation() == Term::And) {