diff --git a/perl/xs-src/unpack.c b/perl/xs-src/unpack.c
index 05d953a8..108f9fda 100644
--- a/perl/xs-src/unpack.c
+++ b/perl/xs-src/unpack.c
@@ -46,37 +46,37 @@ static void template_init(msgpack_unpack_t* u);
 
 static SV* template_data(msgpack_unpack_t* u);
 
-static int template_execute(msgpack_unpack_t* u,
+static int template_execute(msgpack_unpack_t* u PERL_UNUSED_DECL,
     const char* data, size_t len, size_t* off);
 
-STATIC_INLINE SV* template_callback_root(unpack_user* u)
+STATIC_INLINE SV* template_callback_root(unpack_user* u PERL_UNUSED_DECL)
 {
     dTHX;
     return &PL_sv_undef;
 }
 
-STATIC_INLINE int template_callback_uint8(unpack_user* u, uint8_t d, SV** o)
+STATIC_INLINE int template_callback_uint8(unpack_user* u PERL_UNUSED_DECL, uint8_t d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSVuv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_uint16(unpack_user* u, uint16_t d, SV** o)
+STATIC_INLINE int template_callback_uint16(unpack_user* u PERL_UNUSED_DECL, uint16_t d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSVuv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_uint32(unpack_user* u, uint32_t d, SV** o)
+STATIC_INLINE int template_callback_uint32(unpack_user* u PERL_UNUSED_DECL, uint32_t d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSVuv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_uint64(unpack_user* u, uint64_t d, SV** o)
+STATIC_INLINE int template_callback_uint64(unpack_user* u PERL_UNUSED_DECL, uint64_t d, SV** o)
 {
     dTHX;
 #if IVSIZE==4
@@ -101,28 +101,28 @@ STATIC_INLINE int template_callback_int16(unpack_user* u PERL_UNUSED_DECL, int16
     return 0;
 }
 
-STATIC_INLINE int template_callback_int32(unpack_user* u, int32_t d, SV** o)
+STATIC_INLINE int template_callback_int32(unpack_user* u PERL_UNUSED_DECL, int32_t d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSViv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_int64(unpack_user* u, int64_t d, SV** o)
+STATIC_INLINE int template_callback_int64(unpack_user* u PERL_UNUSED_DECL, int64_t d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSViv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_float(unpack_user* u, float d, SV** o)
+STATIC_INLINE int template_callback_float(unpack_user* u PERL_UNUSED_DECL, float d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSVnv(d));
     return 0;
 }
 
-STATIC_INLINE int template_callback_double(unpack_user* u, double d, SV** o)
+STATIC_INLINE int template_callback_double(unpack_user* u PERL_UNUSED_DECL, double d, SV** o)
 {
     dTHX;
     *o = sv_2mortal(newSVnv(d));
@@ -130,27 +130,27 @@ STATIC_INLINE int template_callback_double(unpack_user* u, double d, SV** o)
 }
 
 /* &PL_sv_undef is not so good. see http://gist.github.com/387743 */
-STATIC_INLINE int template_callback_nil(unpack_user* u, SV** o)
+STATIC_INLINE int template_callback_nil(unpack_user* u PERL_UNUSED_DECL, SV** o)
 {
     dTHX;
     *o = sv_newmortal();
     return 0;
 }
 
-STATIC_INLINE int template_callback_true(unpack_user* u, SV** o)
+STATIC_INLINE int template_callback_true(unpack_user* u PERL_UNUSED_DECL, SV** o)
 {
     dTHX;
     *o = get_bool("Data::MessagePack::true");
     return 0;
 }
 
-STATIC_INLINE int template_callback_false(unpack_user* u, SV** o)
+STATIC_INLINE int template_callback_false(unpack_user* u PERL_UNUSED_DECL, SV** o)
 {
     dTHX; *o = get_bool("Data::MessagePack::false");
     return 0;
 }
 
-STATIC_INLINE int template_callback_array(unpack_user* u, unsigned int n, SV** o)
+STATIC_INLINE int template_callback_array(unpack_user* u PERL_UNUSED_DECL, unsigned int n, SV** o)
 {
     dTHX;
     AV* a = (AV*)sv_2mortal((SV*)newAV());
@@ -159,7 +159,7 @@ STATIC_INLINE int template_callback_array(unpack_user* u, unsigned int n, SV** o
     return 0;
 }
 
-STATIC_INLINE int template_callback_array_item(unpack_user* u, SV** c, SV* o)
+STATIC_INLINE int template_callback_array_item(unpack_user* u PERL_UNUSED_DECL, SV** c, SV* o)
 {
     dTHX;
     av_push((AV*)SvRV(*c), o);
@@ -167,7 +167,7 @@ STATIC_INLINE int template_callback_array_item(unpack_user* u, SV** c, SV* o)
     return 0;
 }
 
-STATIC_INLINE int template_callback_map(unpack_user* u, unsigned int n, SV** o)
+STATIC_INLINE int template_callback_map(unpack_user* u PERL_UNUSED_DECL, unsigned int n PERL_UNUSED_DECL, SV** o)
 {
     dTHX;
     HV* h = (HV*)sv_2mortal((SV*)newHV());
@@ -175,15 +175,15 @@ STATIC_INLINE int template_callback_map(unpack_user* u, unsigned int n, SV** o)
     return 0;
 }
 
-STATIC_INLINE int template_callback_map_item(unpack_user* u, SV** c, SV* k, SV* v)
+STATIC_INLINE int template_callback_map_item(unpack_user* u PERL_UNUSED_DECL, SV** c, SV* k, SV* v)
 {
     dTHX;
-    hv_store_ent((HV*)SvRV(*c), k, v, 0);
+    (void)hv_store_ent((HV*)SvRV(*c), k, v, 0);
     SvREFCNT_inc(v);
     return 0;
 }
 
-STATIC_INLINE int template_callback_raw(unpack_user* u, const char* b, const char* p, unsigned int l, SV** o)
+STATIC_INLINE int template_callback_raw(unpack_user* u PERL_UNUSED_DECL, const char* b PERL_UNUSED_DECL, const char* p, unsigned int l, SV** o)
 {
     dTHX;
     /*  *o = newSVpvn_flags(p, l, SVs_TEMP); <= this does not work. */
@@ -203,7 +203,7 @@ STATIC_INLINE int template_callback_raw(unpack_user* u, const char* b, const cha
 STATIC_INLINE SV* _msgpack_unpack(SV* data, int limit) {
     msgpack_unpack_t mp;
     dTHX;
-    unpack_user u = {0, &PL_sv_undef};
+    unpack_user u = {0, &PL_sv_undef, false};
 	int ret;
 	size_t from = 0;
     STRLEN dlen;
@@ -248,7 +248,6 @@ XS(xs_unpack_limit) {
 
 XS(xs_unpack) {
     dXSARGS;
-    msgpack_unpack_t mp;
 
     if (items != 2) {
         Perl_croak(aTHX_ "Usage: Data::MessagePack->unpack('datadata')");
@@ -300,7 +299,7 @@ STATIC_INLINE SV* _execute_impl(SV* self, SV* data, UV off, I32 limit) {
 	long dlen = limit;
 	int ret;
 
-	if(from >= dlen) {
+	if(from >= (size_t)dlen) {
         Perl_croak(aTHX_ "offset is bigger than data buffer size.");
 	}