Fix type safety issue

Makefile

@@ -1,7 +1,11 @@
 CC = gcc
-CFLAGS = -Wall -Wextra -O3 -Isrc/include -Iinclude
+CFLAGS = -Wall -Wextra -Isrc/include -Iinclude
 LDFLAGS = 
 
+# Install paths
+PREFIX ?= /usr/local
+DESTDIR ?=
+
 # Directories
 SRC_DIR = src
 BUILD_DIR = build
@@ -68,6 +72,16 @@ $(BUILD_DIR) $(BIN_DIR) $(LIB_DIR) $(INC_DIR) $(OBJ_DIR):
 clean:
 	rm -rf $(BUILD_DIR)
 
+# Install executable, library, and header
+.PHONY: install
+install: both
+	mkdir -p $(DESTDIR)$(PREFIX)/bin
+	mkdir -p $(DESTDIR)$(PREFIX)/lib
+	mkdir -p $(DESTDIR)$(PREFIX)/include
+	cp $(EXECUTABLE) $(DESTDIR)$(PREFIX)/bin/
+	cp $(SHARED_LIB) $(DESTDIR)$(PREFIX)/lib/
+	cp $(HEADER) $(DESTDIR)$(PREFIX)/include/
+
 # Debug: print variables
 .PHONY: debug
 debug: