diff --git a/client/cs_apps.C b/client/cs_apps.C
index 31e1ec91b0..7bd81bdd92 100644
--- a/client/cs_apps.C
+++ b/client/cs_apps.C
@@ -27,6 +27,7 @@
 #endif
 
 #ifndef _WIN32
+#include <cassert>
 #include <csignal>
 #endif