diff --git a/src/prefiltering/ungappedprefilter.cpp b/src/prefiltering/ungappedprefilter.cpp
index f07fed84..1640dd56 100644
--- a/src/prefiltering/ungappedprefilter.cpp
+++ b/src/prefiltering/ungappedprefilter.cpp
@@ -474,11 +474,14 @@ int prefilterInternal(int argc, const char **argv, const Command &command, int m
 
     resultWriter.close();
 
-
     if(taxonomyHook != NULL){
         delete taxonomyHook;
     }
 
+    if (sequenceLookup != NULL) {
+        delete sequenceLookup;
+    }
+
     if(sameDB == false){
         delete qDbrIdx;
     }