diff --git a/src/client.cpp b/src/client.cpp
index de813187..d2ec7017 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -880,6 +880,7 @@ void Client::ProcessData(NetworkPacket *pkt)
 	if (command >= TOCLIENT_NUM_MSG_TYPES) {
 		infostream << "Client: Ignoring unknown command "
 			<< command << std::endl;
+		return;
 	}
 
 	/*
diff --git a/src/server.cpp b/src/server.cpp
index 52bc9867..0e3d94fa 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -1206,6 +1206,7 @@ void Server::ProcessData(NetworkPacket *pkt)
 		if (command >= TOSERVER_NUM_MSG_TYPES) {
 			infostream << "Server: Ignoring unknown command "
 					 << command << std::endl;
+			return;
 		}
 
 		if (toServerCommandTable[command].state == TOSERVER_STATE_NOT_CONNECTED) {