diff --git a/.dockerignore b/.dockerignore
index 378eac25..b5bff56b 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1 +1,3 @@
 build
+CMakeCache.txt
+ws/CMakeCache.txt
diff --git a/Dockerfile b/Dockerfile
index f08784f7..765a872f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -44,4 +44,5 @@ RUN ldd /usr/local/bin/ws
 USER app
 WORKDIR /home/app
 
-CMD ["ws"]
+ENTRYPOINT ["ws"]
+CMD ["--help"]
diff --git a/ixwebsocket/IXSocketServer.cpp b/ixwebsocket/IXSocketServer.cpp
index 1a8381b0..99e29e6c 100644
--- a/ixwebsocket/IXSocketServer.cpp
+++ b/ixwebsocket/IXSocketServer.cpp
@@ -13,6 +13,7 @@
 #include <sstream>
 #include <future>
 #include <string.h>
+#include <assert.h>
 
 namespace ix
 {