diff --git a/Makefile b/Makefile
index 89778a3..d8d062d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS=-std=c11 -g -fno-common
+CFLAGS=-std=c11 -g -fno-common -Wall -Wno-switch
 
 SRCS=$(wildcard *.c)
 OBJS=$(SRCS:.c=.o)
diff --git a/chibicc.h b/chibicc.h
index 5f16ace..ac2348c 100644
--- a/chibicc.h
+++ b/chibicc.h
@@ -9,6 +9,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdnoreturn.h>
 #include <string.h>
 #include <strings.h>
 #include <sys/stat.h>
@@ -79,9 +80,9 @@ struct Token {
   Token *origin;    // If this is expanded from a macro, the original token
 };
 
-void error(char *fmt, ...);
-void error_at(char *loc, char *fmt, ...);
-void error_tok(Token *tok, char *fmt, ...);
+noreturn void error(char *fmt, ...);
+noreturn void error_at(char *loc, char *fmt, ...);
+noreturn void error_tok(Token *tok, char *fmt, ...);
 void warn_tok(Token *tok, char *fmt, ...);
 bool equal(Token *tok, char *op);
 Token *skip(Token *tok, char *op);