diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..67593d1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,32 @@
+# Local configuration
+config.mk
+
+# Build artifacts
+*.o
+*.d
+*~
+*.exe
+mqjs
+example
+mqjs_stdlib
+mqjs_stdlib.h
+mquickjs_atom.h
+test_builtin.bin
+dtoa_test
+libm_test
+rempio2_test
+
+# Example artifacts
+example_stdlib
+example_stdlib.h
+
+# Extra tests
+mquickjs-extras.tar.xz
+tests/octane/
+tests/dtoa_test.c
+tests/dtoa_test.h
+tests/gay-fixed.c
+tests/gay-precision.c
+tests/gay-shortest.c
+tests/libm_test.c
+tests/rempio2_test.c
diff --git a/Makefile b/Makefile
index 7caa565..85ea593 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,15 @@
-#CONFIG_PROFILE=y
-#CONFIG_X86_32=y
-#CONFIG_ARM32=y
-#CONFIG_WIN32=y
-#CONFIG_SOFTFLOAT=y
-#CONFIG_ASAN=y
-#CONFIG_GPROF=y
-CONFIG_SMALL=y
+CONFIG_PROFILE ?=
+CONFIG_X86_32 ?=
+CONFIG_ARM32 ?=
+CONFIG_WIN32 ?=
+CONFIG_SOFTFLOAT ?=
+CONFIG_ASAN ?=
+CONFIG_GPROF ?=
+CONFIG_SMALL ?= y
 # consider warnings as errors (for development)
-#CONFIG_WERROR=y
+CONFIG_WERROR ?=
+
+-include config.mk
 
 ifdef CONFIG_ARM32
 CROSS_PREFIX=arm-linux-gnu-
@@ -76,7 +78,7 @@ MQJS_BUILD_FLAGS=-m32
 endif
 
 PROGS=mqjs$(EXE) example$(EXE)
-TEST_PROGS=dtoa_test libm_test 
+TEST_PROGS=dtoa_test libm_test rempio2_test
 
 all: $(PROGS)
 
@@ -147,6 +149,6 @@ rempio2_test: tests/rempio2_test.o libm.o
 	$(CC) $(LDFLAGS) -o $@ $^ $(LIBS)
 
 clean:
-	rm -f *.o *.d *~ tests/*.o tests/*.d tests/*~ test_builtin.bin mqjs_stdlib mqjs_stdlib.h mquickjs_build_atoms mquickjs_atom.h mqjs_example example_stdlib example_stdlib.h $(PROGS) $(TEST_PROGS)
+	rm -f *.o *.d *~ tests/*.o tests/*.d tests/*~ test_builtin.bin mqjs_stdlib mqjs_stdlib.h mquickjs_atom.h example_stdlib example_stdlib.h $(PROGS) $(TEST_PROGS)
 
 -include $(wildcard *.d)
diff --git a/README.md b/README.md
index 177a8c5..aa5702f 100644
--- a/README.md
+++ b/README.md
@@ -346,6 +346,22 @@ the C stack usage is bounded. There is no abstract syntax tree. The
 bytecode is generated in one pass with several tricks to optimize it
 (QuickJS has several optimization passes).
 
+#### Configuration
+
+The build configuration can be customized by creating a `config.mk` file.
+You can copy the example configuration:
+
+```bash
+cp config.mk.example config.mk
+```
+
+Then edit `config.mk` to enable or disable specific options (e.g. `CONFIG_ASAN=y` for debugging).
+Alternatively, you can override options directly on the command line:
+
+```bash
+make CONFIG_SMALL=n
+```
+
 ## Tests and benchmarks
 
 Running the basic tests:
diff --git a/config.mk.example b/config.mk.example
new file mode 100644
index 0000000..e3d4e5b
--- /dev/null
+++ b/config.mk.example
@@ -0,0 +1,30 @@
+# Local configuration file for mquickjs
+# Uncomment or set variables to 'y' to enable, or 'n' to disable.
+
+# Enable generic profiling flags (-p)
+#CONFIG_PROFILE=y
+
+# Force 32-bit x86 build
+#CONFIG_X86_32=y
+
+# Force ARM 32-bit build (sets CROSS_PREFIX=arm-linux-gnu- and -mthumb)
+#CONFIG_ARM32=y
+
+# Build for Windows (MinGW)
+#CONFIG_WIN32=y
+
+# Use soft float (software floating point)
+#CONFIG_SOFTFLOAT=y
+
+# Enable AddressSanitizer (ASAN) for debugging memory issues
+#CONFIG_ASAN=y
+
+# Enable profiling (gprof)
+#CONFIG_GPROF=y
+
+# Optimize for small code size (default: y)
+# Set to 'n' to use -O2 instead of -Os
+#CONFIG_SMALL=y
+
+# Treat compiler warnings as errors
+#CONFIG_WERROR=y