diff --git a/src/makefile b/src/makefile
index 701feb3..9768ba1 100644
--- a/src/makefile
+++ b/src/makefile
@@ -48,7 +48,7 @@ CC_linux=gcc
 DEF_linux=-DLUASOCKET_DEBUG \
 	-DLUASOCKET_API='__attribute__((visibility("default")))' \
 	-DMIME_API='__attribute__((visibility("default")))'
-CFLAGS_linux= -I$(LUAINC) $(DEF) -pedantic -Wall -O2 -fpic \
+CFLAGS_linux= -I$(LUAINC) $(DEF) -pedantic -Wall -Wshadow -Wextra -Wimplicit -O2 -ggdb3 -fpic \
 	-fvisibility=hidden
 LDFLAGS_linux=-O -shared -fpic -o 
 LD_linux=gcc
diff --git a/src/mime.c b/src/mime.c
index 218e6f7..a1d7065 100644
--- a/src/mime.c
+++ b/src/mime.c
@@ -35,12 +35,12 @@ static int mime_global_eol(lua_State *L);
 static int mime_global_dot(lua_State *L);
 
 static size_t dot(int c, size_t state, luaL_Buffer *buffer);
-static void b64setup(UC *b64unbase);
+static void b64setup(UC *base);
 static size_t b64encode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 static size_t b64pad(const UC *input, size_t size, luaL_Buffer *buffer);
 static size_t b64decode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 
-static void qpsetup(UC *qpclass, UC *qpunbase);
+static void qpsetup(UC *class, UC *unbase);
 static void qpquote(UC c, luaL_Buffer *buffer);
 static size_t qpdecode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 static size_t qpencode(UC c, UC *input, size_t size, 
@@ -149,12 +149,12 @@ static int mime_global_wrp(lua_State *L)
 /*-------------------------------------------------------------------------*\
 * Fill base64 decode map. 
 \*-------------------------------------------------------------------------*/
-static void b64setup(UC *b64unbase) 
+static void b64setup(UC *unbase) 
 {
     int i;
-    for (i = 0; i <= 255; i++) b64unbase[i] = (UC) 255;
-    for (i = 0; i < 64; i++) b64unbase[b64base[i]] = (UC) i;
-    b64unbase['='] = 0;
+    for (i = 0; i <= 255; i++) unbase[i] = (UC) 255;
+    for (i = 0; i < 64; i++) unbase[b64base[i]] = (UC) i;
+    unbase['='] = 0;
 }
 
 /*-------------------------------------------------------------------------*\
@@ -349,24 +349,24 @@ static int mime_global_unb64(lua_State *L)
 * Split quoted-printable characters into classes
 * Precompute reverse map for encoding
 \*-------------------------------------------------------------------------*/
-static void qpsetup(UC *qpclass, UC *qpunbase)
+static void qpsetup(UC *cl, UC *unbase)
 {
     int i;
-    for (i = 0; i < 256; i++) qpclass[i] = QP_QUOTED;
-    for (i = 33; i <= 60; i++) qpclass[i] = QP_PLAIN;
-    for (i = 62; i <= 126; i++) qpclass[i] = QP_PLAIN;
-    qpclass['\t'] = QP_IF_LAST; 
-    qpclass[' '] = QP_IF_LAST;
-    qpclass['\r'] = QP_CR;
-    for (i = 0; i < 256; i++) qpunbase[i] = 255;
-    qpunbase['0'] = 0; qpunbase['1'] = 1; qpunbase['2'] = 2;
-    qpunbase['3'] = 3; qpunbase['4'] = 4; qpunbase['5'] = 5;
-    qpunbase['6'] = 6; qpunbase['7'] = 7; qpunbase['8'] = 8;
-    qpunbase['9'] = 9; qpunbase['A'] = 10; qpunbase['a'] = 10;
-    qpunbase['B'] = 11; qpunbase['b'] = 11; qpunbase['C'] = 12;
-    qpunbase['c'] = 12; qpunbase['D'] = 13; qpunbase['d'] = 13;
-    qpunbase['E'] = 14; qpunbase['e'] = 14; qpunbase['F'] = 15;
-    qpunbase['f'] = 15;
+    for (i = 0; i < 256; i++) cl[i] = QP_QUOTED;
+    for (i = 33; i <= 60; i++) cl[i] = QP_PLAIN;
+    for (i = 62; i <= 126; i++) cl[i] = QP_PLAIN;
+    cl['\t'] = QP_IF_LAST; 
+    cl[' '] = QP_IF_LAST;
+    cl['\r'] = QP_CR;
+    for (i = 0; i < 256; i++) unbase[i] = 255;
+    unbase['0'] = 0; unbase['1'] = 1; unbase['2'] = 2;
+    unbase['3'] = 3; unbase['4'] = 4; unbase['5'] = 5;
+    unbase['6'] = 6; unbase['7'] = 7; unbase['8'] = 8;
+    unbase['9'] = 9; unbase['A'] = 10; unbase['a'] = 10;
+    unbase['B'] = 11; unbase['b'] = 11; unbase['C'] = 12;
+    unbase['c'] = 12; unbase['D'] = 13; unbase['d'] = 13;
+    unbase['E'] = 14; unbase['e'] = 14; unbase['F'] = 15;
+    unbase['f'] = 15;
 }
 
 /*-------------------------------------------------------------------------*\
diff --git a/src/tcp.c b/src/tcp.c
index 3204b40..658f255 100644
--- a/src/tcp.c
+++ b/src/tcp.c
@@ -40,7 +40,7 @@ static int meth_setfd(lua_State *L);
 static int meth_dirty(lua_State *L);
 
 /* tcp object methods */
-static luaL_reg tcp[] = {
+static luaL_reg tcp_methods[] = {
     {"__gc",        meth_close},
     {"__tostring",  auxiliar_tostring},
     {"accept",      meth_accept},
@@ -88,9 +88,9 @@ static luaL_reg func[] = {
 int tcp_open(lua_State *L)
 {
     /* create classes */
-    auxiliar_newclass(L, "tcp{master}", tcp);
-    auxiliar_newclass(L, "tcp{client}", tcp);
-    auxiliar_newclass(L, "tcp{server}", tcp);
+    auxiliar_newclass(L, "tcp{master}", tcp_methods);
+    auxiliar_newclass(L, "tcp{client}", tcp_methods);
+    auxiliar_newclass(L, "tcp{server}", tcp_methods);
     /* create class groups */
     auxiliar_add2group(L, "tcp{master}", "tcp{any}");
     auxiliar_add2group(L, "tcp{client}", "tcp{any}");
@@ -359,7 +359,7 @@ static const char *trybind6(const char *localaddr, const char *localserv,
     for (iterator = resolved; iterator; iterator = iterator->ai_next) {
         /* create a new socket each time because parameters
          * may have changed */
-        const char *err = socket_strerror(socket_create(&tcp->sock, 
+        err = socket_strerror(socket_create(&tcp->sock, 
             iterator->ai_family, iterator->ai_socktype, 
             iterator->ai_protocol));
         /* if failed to create socket, bail out */
@@ -445,7 +445,7 @@ static const char *tryconnect6(const char *remoteaddr, const char *remoteserv,
         p_timeout tm = timeout_markstart(&tcp->tm);
         /* create new socket if one wasn't created by the bind stage */
         if (tcp->sock == SOCKET_INVALID) {
-            const char *err = socket_strerror(socket_create(&tcp->sock, 
+            err = socket_strerror(socket_create(&tcp->sock, 
                 iterator->ai_family, iterator->ai_socktype, 
                 iterator->ai_protocol));
             if (err != NULL) {
diff --git a/src/udp.c b/src/udp.c
index e3c86e7..0f9b7cc 100644
--- a/src/udp.c
+++ b/src/udp.c
@@ -44,7 +44,7 @@ static int meth_setfd(lua_State *L);
 static int meth_dirty(lua_State *L);
 
 /* udp object methods */
-static luaL_reg udp[] = {
+static luaL_reg udp_methods[] = {
     {"__gc",        meth_close},
     {"__tostring",  auxiliar_tostring},
     {"close",       meth_close},
@@ -98,8 +98,8 @@ static luaL_reg func[] = {
 int udp_open(lua_State *L)
 {
     /* create classes */
-    auxiliar_newclass(L, "udp{connected}", udp);
-    auxiliar_newclass(L, "udp{unconnected}", udp);
+    auxiliar_newclass(L, "udp{connected}", udp_methods);
+    auxiliar_newclass(L, "udp{unconnected}", udp_methods);
     /* create class groups */
     auxiliar_add2group(L, "udp{connected}",   "udp{any}");
     auxiliar_add2group(L, "udp{unconnected}", "udp{any}");