diff --git a/.common/makefile b/.common/makefile
index 58c3485..31bc2b7 100644
--- a/.common/makefile
+++ b/.common/makefile
@@ -1,8 +1,11 @@
 CXX=clang++
 CXXFLAGS=-std=c++20 -Wall -Wextra
 
-%: format %.cpp
-	$(CXX) $(CXXFLAGS) -g $^ -o $@
+catch2.o: ../.common/catch_amalgamated.cpp ../.common/catch_amalgamated.hpp
+	$(CXX) $(CXXFLAGS) -g -c ../.common/catch_amalgamated.cpp -o catch2.o
+
+%: catch2.o %.cpp
+	$(CXX) $(CXXFLAGS) -DTEST -g $^ -o $@
 
 format:
 	clang-format -i -style=google *.cpp