diff --git a/sources.cmake b/sources.cmake
index 7d47732..6508d32 100644
--- a/sources.cmake
+++ b/sources.cmake
@@ -1,5 +1,6 @@
 set(erc_sources
 	apple2.c
+	apple2.dd.c
 	log.c
 	mos6502.c
 	mos6502.addr.c