diff --git a/ixwebsocket/IXHttpClient.cpp b/ixwebsocket/IXHttpClient.cpp
index 5ff137e7..d34eeed3 100644
--- a/ixwebsocket/IXHttpClient.cpp
+++ b/ixwebsocket/IXHttpClient.cpp
@@ -16,7 +16,10 @@
 #include <random>
 #include <sstream>
 #include <vector>
+
+#ifdef IXWEBSOCKET_USE_ZLIB
 #include <zlib.h>
+#endif
 
 namespace ix
 {
diff --git a/ixwebsocket/IXHttpServer.cpp b/ixwebsocket/IXHttpServer.cpp
index 09ceb668..08fc3a4c 100644
--- a/ixwebsocket/IXHttpServer.cpp
+++ b/ixwebsocket/IXHttpServer.cpp
@@ -13,7 +13,10 @@
 #include <fstream>
 #include <sstream>
 #include <vector>
+
+#ifdef IXWEBSOCKET_USE_ZLIB
 #include <zlib.h>
+#endif
 
 namespace
 {