diff --git a/src/flow-timeout.c b/src/flow-timeout.c
index 90a97fa666..546fc35fe9 100644
--- a/src/flow-timeout.c
+++ b/src/flow-timeout.c
@@ -211,7 +211,7 @@ static inline Packet *FlowForceReassemblyPseudoPacketSetup(
     }
 
     p->tcph->th_offx2 = 0x50;
-    p->tcph->th_flags |= TH_ACK;
+    p->tcph->th_flags = 0;
     p->tcph->th_win = 10;
     p->tcph->th_urp = 0;