diff --git a/bin/Makefile b/bin/Makefile
index 225ba8d..6b4932d 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -29,7 +29,7 @@ ifeq ($(OS),LINUX)
 	CFLAGS += -D_POSIX_SOURCE
 endif
 ifdef DEBUG
-CFLAGS += -W -Wall -Wextra -Wmissing-prototypes -Winline -Wcast-align \
+CFLAGS += -W -Wall -Wextra -Wpointer-arith -Wmissing-prototypes -Winline -Wcast-align \
 					-Wmissing-declarations -fno-inline -g3 -DDEBUG -DLUA_USE_APICHECK -std=c99
 else
 CFLAGS += -O2 -funroll-loops -pipe -std=c99
diff --git a/src/pack.c b/src/pack.c
index 46d5fbd..fb7ce46 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -382,6 +382,7 @@ long pack_tell(Packfile* file) {
 void* pack_readfile(const char* packfile, const char* filename, uint32_t* filesize) {
   Packfile* file = (Packfile*)malloc(sizeof(Packfile));
   void* buf;
+  char* str;
   int size, bytes;
 
   if(filesize)
@@ -409,7 +410,8 @@ void* pack_readfile(const char* packfile, const char* filename, uint32_t* filesi
     return NULL;
   }
   DEBUG("Read %d bytes from '%s'", bytes, filename);
-  memset(buf+size, 0, 1); /* Append size '\0' for it to validate as a string. */
+  str = buf;
+  str[size] = '\0'; /* Append size '\0' for it to validate as a string. */
 
   /* Check the md5. */
   md5_state_t md5;