  OBJS := $(SOURCES:cc=o)
  
 diff --git a/yosys-symbiflow-plugins/Makefile_test.common b/yosys-symbiflow-plugins/Makefile_test.common
-index 1490199..0b5c750 100644
+index 61abadb..3701193 100644
 --- a/yosys-symbiflow-plugins/Makefile_test.common
 +++ b/yosys-symbiflow-plugins/Makefile_test.common
 @@ -14,21 +14,21 @@

+$(error "Didn't find 'uhdm-yosys-config' under '$(YOSYS_PATH)'")
 endif
 
-GTEST_DIR ?= ../../third_party/googletest/googletest
-CXX ?= $(shell $(YOSYS_CONFIG) --cxx)
-CXXFLAGS ?= $(shell $(YOSYS_CONFIG) --cxxflags) -I.. -I$(GTEST_DIR)/include
-LDLIBS ?= $(shell $(YOSYS_CONFIG) --ldlibs) -L$(GTEST_DIR)/build/lib -lgtest -lgtest_main -lpthread
-LDFLAGS ?= $(shell $(YOSYS_CONFIG) --ldflags)
-TEST_UTILS ?= ../../../test-utils/test-utils.tcl
+GTEST_DIR = ../../third_party/googletest/googletest
+CXX = $(shell $(YOSYS_CONFIG) --cxx)
+CXXFLAGS = $(shell $(YOSYS_CONFIG) --cxxflags) -I.. -I$(GTEST_DIR)/include
+LDLIBS = $(shell $(YOSYS_CONFIG) --ldlibs) -L$(GTEST_DIR)/build/lib -lgtest -lgtest_main -lpthread
+LDFLAGS = $(shell $(YOSYS_CONFIG) --ldflags)
+TEST_UTILS = ../../../test-utils/test-utils.tcl

diff --git a/yosys-symbiflow-plugins/Makefile_plugin.common b/yosys-symbiflow-plugins/Makefile_plugin.common
index 0870f21..47d118e 100644
--- a/yosys-symbiflow-plugins/Makefile_plugin.common
+++ b/yosys-symbiflow-plugins/Makefile_plugin.common
@@ -38,22 +38,22 @@
