diff --git a/clientgui/Makefile.am b/clientgui/Makefile.am
index baa5ccdea7..1f3c7bd385 100644
--- a/clientgui/Makefile.am
+++ b/clientgui/Makefile.am
@@ -27,6 +27,7 @@ boinc_gui_SOURCES = \
     ViewResources.cpp \
     ViewTransfers.cpp \
     ViewWork.cpp \
+    ../lib/diagnostics.C \
     ../lib/gui_rpc_client.C \
     ../lib/filesys.C \
     ../lib/mfile.C \