Add good error handling
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8fc9b17..050b299 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,5 +21,6 @@
 	set(THREAD pthread)
 endif()
 
-add_executable(6502 main.c cpu.c cpu.h dbg.c dbg.h instructions.h gui.h gui.c screen.h screen.c)
+add_executable(6502 main.c cpu.c cpu.h dbg.c dbg.h 
+	instructions.h gui.h gui.c screen.h screen.c common.h common.c)
 target_link_libraries(6502 readline SDL2 GL GLU GLEW m ${THREAD})