diff --git a/lib/radio/ddc/ghdl/tb_ddc.make b/lib/radio/ddc/ghdl/tb_ddc.make
index 8f8cb2a..6bece9f 100644
--- a/lib/radio/ddc/ghdl/tb_ddc.make
+++ b/lib/radio/ddc/ghdl/tb_ddc.make
@@ -18,6 +18,7 @@ SRCS += $(LIB_PATH)/radio/ddc/src/tb_ddc.vhd
 TARGET := tb_ddc
 ENTITY := tb_ddc
 RUN_TIME := 100us
+WAVE_FORMAT := vcd
 
 GHDL_OPTS := -P$(LIB_PATH)/fixed/ieee_proposed/build/fixed_pkg/ieee_proposed
 
diff --git a/lib/radio/ddc/ghdl/tb_syn_ddc.make b/lib/radio/ddc/ghdl/tb_syn_ddc.make
index b14691f..a5e8ec9 100644
--- a/lib/radio/ddc/ghdl/tb_syn_ddc.make
+++ b/lib/radio/ddc/ghdl/tb_syn_ddc.make
@@ -22,6 +22,7 @@ SRCS += $(LIB_PATH)/radio/ddc/src/tb_syn_ddc.vhd
 TARGET := tb_syn_ddc
 ENTITY := tb_syn_ddc
 RUN_TIME := 100us
+WAVE_FORMAT := vcd
 
 GHDL_OPTS := -P$(LIB_PATH)/fixed/ieee_proposed/build/fixed_pkg/ieee_proposed