diff -uNr wren-0.1.0/util/wren.mk wren-0.1.0.mod/util/wren.mk
--- wren-0.1.0/util/wren.mk	2016-05-21 20:53:05.000000000 +0300
+++ wren-0.1.0.mod/util/wren.mk	2019-07-01 21:55:56.761159939 +0300
@@ -42,11 +42,11 @@
 # Mode configuration.
 ifeq ($(MODE),debug)
 	WREN := wrend
-	C_OPTIONS += -O0 -DDEBUG -g
+	C_OPTIONS += -DDEBUG -g $(CFLAGS) $(CPPFLAGS)
 	BUILD_DIR := $(BUILD_DIR)/debug
 else
 	WREN += wren
-	C_OPTIONS += -O3
+	C_OPTIONS += $(CFLAGS) $(CPPFLAGS)
 	BUILD_DIR := $(BUILD_DIR)/release
 endif
 
@@ -106,8 +106,6 @@
 	# Link in the right libraries needed by libuv on Windows and Linux.
 	ifeq ($(OS),mingw32)
 		LIBUV_LIBS := -lws2_32 -liphlpapi -lpsapi -luserenv
-	else
-		LIBUV_LIBS := -lpthread -lrt
 	endif
 endif
 
@@ -119,13 +117,9 @@
 VM_OBJECTS     := $(addprefix $(BUILD_DIR)/vm/, $(notdir $(VM_SOURCES:.c=.o)))
 TEST_OBJECTS   := $(patsubst test/api/%.c, $(BUILD_DIR)/test/%.o, $(TEST_SOURCES))
 
-LIBUV_DIR := deps/libuv
-LIBUV     := build/libuv$(LIBUV_ARCH).a
-
 # Flags needed to compile source files for the CLI, including the modules and
 # API tests.
-CLI_FLAGS := -D_XOPEN_SOURCE=600 -Isrc/include -I$(LIBUV_DIR)/include \
-             -Isrc/cli -Isrc/module
+CLI_FLAGS := -D_XOPEN_SOURCE=600 -Isrc/include -Isrc/cli -Isrc/module
 
 # Targets ---------------------------------------------------------------------
 
@@ -148,11 +142,10 @@
 test: $(BUILD_DIR)/test/$(WREN)
 
 # Command-line interpreter.
-bin/$(WREN): $(OPT_OBJECTS) $(CLI_OBJECTS) $(MODULE_OBJECTS) $(VM_OBJECTS) \
-		$(LIBUV)
+bin/$(WREN): $(OPT_OBJECTS) $(CLI_OBJECTS) $(MODULE_OBJECTS) $(VM_OBJECTS)
 	@ printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
 	@ mkdir -p bin
-	@ $(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
+	@ $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) -lm -luv
 
 # Static library.
 lib/lib$(WREN).a: $(OPT_OBJECTS) $(VM_OBJECTS)
@@ -168,21 +161,21 @@
 
 # Test executable.
 $(BUILD_DIR)/test/$(WREN): $(OPT_OBJECTS) $(MODULE_OBJECTS) $(TEST_OBJECTS) \
-		$(VM_OBJECTS) $(BUILD_DIR)/cli/modules.o $(BUILD_DIR)/cli/vm.o $(LIBUV)
+		$(VM_OBJECTS) $(BUILD_DIR)/cli/modules.o $(BUILD_DIR)/cli/vm.o
 	@ printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
 	@ mkdir -p $(BUILD_DIR)/test
-	@ $(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
+	@ $(CC) $(CFLAGS) $^ -o $@ -lm -luv
 
 # CLI object files.
 $(BUILD_DIR)/cli/%.o: src/cli/%.c $(CLI_HEADERS) $(MODULE_HEADERS) \
-		$(VM_HEADERS) $(LIBUV)
+		$(VM_HEADERS)
 	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
 	@ mkdir -p $(BUILD_DIR)/cli
 	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
 
 # Module object files.
 $(BUILD_DIR)/module/%.o: src/module/%.c $(CLI_HEADERS) $(MODULE_HEADERS) \
-		$(VM_HEADERS) $(LIBUV)
+		$(VM_HEADERS)
 	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
 	@ mkdir -p $(BUILD_DIR)/module
 	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
@@ -201,19 +194,11 @@
 
 # Test object files.
 $(BUILD_DIR)/test/%.o: test/api/%.c $(OPT_HEADERS) $(MODULE_HEADERS) \
-		 $(VM_HEADERS) $(TEST_HEADERS) $(LIBUV)
+		 $(VM_HEADERS) $(TEST_HEADERS)
 	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
 	@ mkdir -p $(dir $@)
 	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
 
-# Download libuv.
-$(LIBUV_DIR)/build/gyp/gyp: util/libuv.py
-	@ ./util/libuv.py download
-
-# Build libuv to a static library.
-$(LIBUV): $(LIBUV_DIR)/build/gyp/gyp util/libuv.py
-	@ ./util/libuv.py build $(LIBUV_ARCH)
-
 # Wren modules that get compiled into the binary as C strings.
 src/optional/wren_opt_%.wren.inc: src/optional/wren_opt_%.wren util/wren_to_c_string.py
 	@ printf "%10s %-30s %s\n" str $<