diff --git a/lib/CPUs/MIPS/ghdl/tb_mips_top.make b/lib/CPUs/MIPS/ghdl/tb_mips_top.make
index bbfa40e..0fd97dc 100644
--- a/lib/CPUs/MIPS/ghdl/tb_mips_top.make
+++ b/lib/CPUs/MIPS/ghdl/tb_mips_top.make
@@ -31,8 +31,8 @@ SRCS += ../src/tb_mips_top.vhd
 
 # Compile
 TARGET := tb_mips_top
-ENTITY = tb_mips_top
-RUN_TIME := 1500us
+ENTITY := tb_mips_top
+RUN_TIME ?= 1500us
 
 include $(VHDL_HOME)/make/ghdl.mk