diff --git a/SConstruct b/SConstruct
index c2873bc..27031a9 100644
--- a/SConstruct
+++ b/SConstruct
@@ -59,7 +59,8 @@ env.Append(CFLAGS = [ "-Wshadow", "-Wno-typedef-redefinition" ])
 #env.Append(CXXFLAGS = [ "-Wno-non-template-friend", "-Woverloaded-virtual",
 #                        "-Wcast-qual", "-Wcast-align", "-Wconversion",
 #                        "-Weffc++", "-std=c++0x", "-Werror" ])
-env.Append(CPPFLAGS = [ "-fno-builtin", "-fno-stack-protector" ])
+env.Append(CPPFLAGS = [ "-fno-builtin", "-fno-stack-protector",
+                        "-Wformat=2", "-Wmissing-format-attribute" ])
 
 if env["WITH_GPROF"] == "1":
     env.Append(CPPFLAGS = [ "-pg" ])
diff --git a/include/stdio.h b/include/stdio.h
index 061639e..3c24d35 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -3,6 +3,7 @@
 #define __STDIO_H__
 
 #include <sys/types.h>
+#include <sys/cdefs.h>
 
 typedef struct FILE {
     int			in_use;
@@ -40,7 +41,7 @@ int puts(const char *str);
 int printf(const char *fmt, ...);
 int fprintf(FILE *stream, const char *fmt, ...);
 int sprintf(char *str, const char *fmt, ...);
-int snprintf(char *str, size_t size, const char *fmt, ...);
+int snprintf(char *str, size_t size, const char *fmt, ...) __printflike(3, 4);;
 
 #endif /* __STDIO_H__ */
 
diff --git a/sys/include/cdefs.h b/sys/include/cdefs.h
index 85ec7ed..5445f23 100644
--- a/sys/include/cdefs.h
+++ b/sys/include/cdefs.h
@@ -16,5 +16,7 @@
 
 #define __hidden	__attribute__((__visibility__("hidden")))
 
+#define __printflike(_fmt, _var) __attribute__((__format__(__printf__, _fmt, _var)))
+
 #endif /* __CDEFS_H__ */