diff --git a/Makefile b/Makefile
index 93091bd6d..fced3c4ae 100644
--- a/Makefile
+++ b/Makefile
@@ -95,14 +95,14 @@ TARGETS = $(PROGRAM_PREFIX)yosys$(EXE) $(PROGRAM_PREFIX)yosys-config
 PRETTY = 1
 SMALL = 0
 
-# Unit test
-UNITESTPATH := tests/unit
-
 all: top-all
 
 YOSYS_SRC := $(dir $(firstword $(MAKEFILE_LIST)))
 VPATH := $(YOSYS_SRC)
 
+# Unit test
+UNITESTPATH := $(YOSYS_SRC)/tests/unit
+
 export CXXSTD ?= c++17
 CXXFLAGS := $(CXXFLAGS) -Wall -Wextra -ggdb -I. -I"$(YOSYS_SRC)" -MD -MP -D_YOSYS_ -fPIC -I$(PREFIX)/include
 LIBS := $(LIBS) -lstdc++ -lm
@@ -1135,7 +1135,7 @@ DOC_TARGET ?= html
 docs: docs/prep
 	$(Q) $(MAKE) -C docs $(DOC_TARGET)
 
-clean: clean-py
+clean: clean-py clean-unit-test
 	rm -rf share
 	rm -f $(OBJS) $(GENFILES) $(TARGETS) $(EXTRA_TARGETS) $(EXTRA_OBJS)
 	rm -f kernel/version_*.o kernel/version_*.cc
@@ -1150,7 +1150,7 @@ clean: clean-py
 	rm -f tests/svinterfaces/*.log_stdout tests/svinterfaces/*.log_stderr tests/svinterfaces/dut_result.txt tests/svinterfaces/reference_result.txt tests/svinterfaces/a.out tests/svinterfaces/*_syn.v tests/svinterfaces/*.diff
 	rm -f  tests/tools/cmp_tbdata
 	rm -f $(addsuffix /run-test.mk,$(MK_TEST_DIRS))
-	-$(MAKE) -C docs clean
+	-$(MAKE) -C $(YOSYS_SRC)/docs clean
 	rm -rf docs/util/__pycache__
 	rm -f libyosys.so
 
@@ -1162,7 +1162,7 @@ clean-py:
 	rm -rf kernel/*.pyh
 
 clean-abc:
-	$(MAKE) -C abc DEP= clean
+	$(MAKE) -C $(YOSYS_SRC)/abc DEP= clean
 	rm -f $(PROGRAM_PREFIX)yosys-abc$(EXE) $(PROGRAM_PREFIX)yosys-libabc.a abc/abc-[0-9a-f]* abc/libabc-[0-9a-f]*.a .git-abc-submodule-hash
 
 mrproper: clean
diff --git a/tests/unit/Makefile b/tests/unit/Makefile
index eee60ef9f..b275d7f41 100644
--- a/tests/unit/Makefile
+++ b/tests/unit/Makefile
@@ -30,11 +30,11 @@ TESTS := $(addprefix $(BINTEST)/, $(basename $(ALLTESTFILE:%Test.cc=%Test.o)))
 
 all: prepare $(TESTS) run-tests
 
-$(BINTEST)/%: $(OBJTEST)/%.o
+$(BINTEST)/%: $(OBJTEST)/%.o | prepare
 	$(CXX) -L$(ROOTPATH) $(RPATH) $(LINKFLAGS) -o $@ $^ $(LIBS) \
 		$(GTEST_LDFLAGS) $(EXTRAFLAGS)
 
-$(OBJTEST)/%.o: $(basename $(subst $(OBJTEST),.,%)).cc
+$(OBJTEST)/%.o: $(basename $(subst $(OBJTEST),.,%)).cc | prepare
 	$(CXX) -o $@ -c -I$(ROOTPATH) $(CPPFLAGS) $(CXXFLAGS) $(GTEST_CXXFLAGS) $^
 
 .PHONY: prepare run-tests clean