forgot to pass CPPFLAGS

test/Makefile

@@ -4,7 +4,7 @@
 
 # additional flags
 CXXFLAGS += -std=c++11 -Wall -Wextra -pedantic -Weffc++ -Wcast-align -Wcast-qual -Wctor-dtor-privacy -Wdisabled-optimization -Wformat=2 -Winit-self -Wmissing-declarations -Wmissing-include-dirs -Wold-style-cast -Woverloaded-virtual -Wredundant-decls -Wshadow -Wsign-conversion -Wsign-promo -Wstrict-overflow=5 -Wswitch -Wundef -Wno-unused -Wnon-virtual-dtor -Wreorder -Wdeprecated -Wfloat-equal
-INCDIRS = -I ../src -I .
+CPPFLAGS += -I ../src -I .
 
 SOURCES = src/unit-runner.cpp src/unit.cpp
 OBJECTS = $(SOURCES:.cpp=.o)
@@ -15,7 +15,7 @@ json_unit: $(OBJECTS) ../src/json.hpp src/catch.hpp
 	$(CXX) $(CXXFLAGS) $(LDFLAGS) $(OBJECTS) -o $@
 
 %.o: %.cpp
-	$(CXX) $(CXXFLAGS) $(INCDIRS) -c $< -o $@
+	$(CXX) $(CXXFLAGS) $(CPPFLAGS) -c $< -o $@
 
 clean:
 	rm -fr json_unit $(OBJECTS)