diff --git a/pack_template.h b/pack_template.h
index 70064783..e12a7a0e 100644
--- a/pack_template.h
+++ b/pack_template.h
@@ -713,7 +713,7 @@ msgpack_pack_inline_func(_false)(msgpack_pack_user x)
 msgpack_pack_inline_func(_array)(msgpack_pack_user x, size_t n)
 {
 	if(n < 16) {
-		unsigned char d = 0x90 | n;
+		unsigned char d = 0x90 | (uint8_t)n;
 		msgpack_pack_append_buffer(x, &d, 1);
 	} else if(n < 65536) {
 		unsigned char buf[3];
@@ -734,7 +734,7 @@ msgpack_pack_inline_func(_array)(msgpack_pack_user x, size_t n)
 msgpack_pack_inline_func(_map)(msgpack_pack_user x, size_t n)
 {
 	if(n < 16) {
-		unsigned char d = 0x80 | n;
+		unsigned char d = 0x80 | (uint8_t)n;
 		msgpack_pack_append_buffer(x, &TAKE8_8(d), 1);
 	} else if(n < 65536) {
 		unsigned char buf[3];
diff --git a/src/msgpack/vrefbuffer.h b/src/msgpack/vrefbuffer.h
index b228b048..23022a84 100644
--- a/src/msgpack/vrefbuffer.h
+++ b/src/msgpack/vrefbuffer.h
@@ -131,7 +131,7 @@ static inline const struct iovec* msgpack_vrefbuffer_vec(const msgpack_vrefbuffe
 
 static inline size_t msgpack_vrefbuffer_veclen(const msgpack_vrefbuffer* vref)
 {
-	return vref->tail - vref->array;
+	return (size_t)(vref->tail - vref->array);
 }
 
 
diff --git a/src/unpack.c b/src/unpack.c
index 5262b958..3186c855 100644
--- a/src/unpack.c
+++ b/src/unpack.c
@@ -71,19 +71,19 @@ static inline int template_callback_uint64(unpack_user* u, uint64_t d, msgpack_o
 { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
 
 static inline int template_callback_int8(unpack_user* u, int8_t d, msgpack_object* o)
-{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
+{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = (uint64_t)d; return 0; }
 		else { o->type = MSGPACK_OBJECT_NEGATIVE_INTEGER; o->via.i64 = d; return 0; } }
 
 static inline int template_callback_int16(unpack_user* u, int16_t d, msgpack_object* o)
-{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
+{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = (uint64_t)d; return 0; }
 		else { o->type = MSGPACK_OBJECT_NEGATIVE_INTEGER; o->via.i64 = d; return 0; } }
 
 static inline int template_callback_int32(unpack_user* u, int32_t d, msgpack_object* o)
-{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
+{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = (uint64_t)d; return 0; }
 		else { o->type = MSGPACK_OBJECT_NEGATIVE_INTEGER; o->via.i64 = d; return 0; } }
 
 static inline int template_callback_int64(unpack_user* u, int64_t d, msgpack_object* o)
-{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
+{ if(d >= 0) { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = (uint64_t)d; return 0; }
 		else { o->type = MSGPACK_OBJECT_NEGATIVE_INTEGER; o->via.i64 = d; return 0; } }
 
 static inline int template_callback_float(unpack_user* u, float d, msgpack_object* o)
diff --git a/src/vrefbuffer.c b/src/vrefbuffer.c
index 19c4cfc4..d43fb6d2 100644
--- a/src/vrefbuffer.c
+++ b/src/vrefbuffer.c
@@ -98,7 +98,7 @@ int msgpack_vrefbuffer_append_ref(msgpack_vrefbuffer* vbuf,
 		const char* buf, size_t len)
 {
 	if(vbuf->tail == vbuf->end) {
-		const size_t nused = vbuf->tail - vbuf->array;
+		const size_t nused = (size_t)(vbuf->tail - vbuf->array);
 		const size_t nnext = nused * 2;
 
 		struct iovec* nvec = (struct iovec*)realloc(
@@ -169,11 +169,11 @@ int msgpack_vrefbuffer_migrate(msgpack_vrefbuffer* vbuf, msgpack_vrefbuffer* to)
 	empty->next = NULL;
 
 
-	const size_t nused = vbuf->tail - vbuf->array;
+	const size_t nused = (size_t)(vbuf->tail - vbuf->array);
 	if(to->tail + nused < vbuf->end) {
-		const size_t tosize = to->tail - to->array;
+		const size_t tosize = (size_t)(to->tail - to->array);
 		const size_t reqsize = nused + tosize;
-		size_t nnext = (to->end - to->array) * 2;
+		size_t nnext = (size_t)(to->end - to->array) * 2;
 		while(nnext < reqsize) {
 			nnext *= 2;
 		}
diff --git a/src/zone.c b/src/zone.c
index ce9a58d5..f982cf7c 100644
--- a/src/zone.c
+++ b/src/zone.c
@@ -127,7 +127,7 @@ bool msgpack_zone_push_finalizer_expand(msgpack_zone* zone,
 {
 	msgpack_zone_finalizer_array* const fa = &zone->finalizer_array;
 
-	const size_t nused = fa->end - fa->array;
+	const size_t nused = (size_t)(fa->end - fa->array);
 
 	size_t nnext;
 	if(nused == 0) {
diff --git a/unpack_template.h b/unpack_template.h
index c4816e4a..60611c6c 100644
--- a/unpack_template.h
+++ b/unpack_template.h
@@ -232,7 +232,7 @@ msgpack_unpack_func(int, _execute)(msgpack_unpack_struct(_context)* ctx, const c
 				case 0xdd:  // array 32
 				case 0xde:  // map 16
 				case 0xdf:  // map 32
-					again_fixed_trail(NEXT_CS(p), 2 << (((unsigned int)*p) & 0x01));
+					again_fixed_trail(NEXT_CS(p), 2u << (((unsigned int)*p) & 0x01));
 				default:
 					goto _failed;
 				}
@@ -397,7 +397,7 @@ _end:
 	ctx->cs = cs;
 	ctx->trail = trail;
 	ctx->top = top;
-	*off = p - (const unsigned char*)data;
+	*off = (size_t)(p - (const unsigned char*)data);
 
 	return ret;
 }