diff --git a/vncviewer/CMakeLists.txt b/vncviewer/CMakeLists.txt
index 742ba13..6a9f8ef 100644
--- a/vncviewer/CMakeLists.txt
+++ b/vncviewer/CMakeLists.txt
@@ -7,6 +7,7 @@
   DesktopWindow.cxx
   UserDialog.cxx
   parameters.cxx
+  keysym2ucs.c
   vncviewer.cxx)
 
 target_link_libraries(vncviewer rfb network rdr os Xregion ${FLTK_LIBRARIES})