diff --git a/skeletons/tests/check-ber_tlv_tag.c b/skeletons/tests/check-ber_tlv_tag.c
new file mode 100644
index 0000000..4118420
--- /dev/null
+++ b/skeletons/tests/check-ber_tlv_tag.c
@@ -0,0 +1,146 @@
+#include <stdio.h>
+#include <assert.h>
+
+#include <ber_tlv_tag.c>
+
+struct tag_control_s {
+	int taglen;
+	uint8_t tagbuf[8];
+
+	int correctly_decodable;
+
+	int tclass;		/* Tag class */
+	ber_tlv_tag_t tvalue;	/* Tag value */
+	int constr;		/* Is it constructed? */
+} control[] = {
+	{ 1, { 0x2 << 6 }, 	1, ASN_TAG_CLASS_CONTEXT, 0, 0 },
+	{ 1, { 0x2 << 6 | 32 | 1 }, 1, ASN_TAG_CLASS_CONTEXT, 1, 1 },
+	{ 1, { 0x3 << 6 | 30 }, 1, ASN_TAG_CLASS_PRIVATE, 30, 0 },
+	{ 1, { 29 }, 		1, ASN_TAG_CLASS_UNIVERSAL, 29, 0 },
+	{ 1, { 0xbf, 31 }, 	0, ASN_TAG_CLASS_CONTEXT, 31, 1 },
+	{ 2, { 0xbf, 31 }, 	1, ASN_TAG_CLASS_CONTEXT, 31, 1 },
+	{ 2, { 0xbf, 127 }, 	1, ASN_TAG_CLASS_CONTEXT, 127, 1 },
+	{ 2, { 0xbf, 129 }, 	0, ASN_TAG_CLASS_CONTEXT, 127, 1 },
+	{ 3, { 0xbf, 129, 0 }, 	1, ASN_TAG_CLASS_CONTEXT, 128, 1 },
+	{ 3, { 0xbf, 129, 1 }, 	1, ASN_TAG_CLASS_CONTEXT, 129, 1 },
+	{ 3, { 0xbf, 130, 0 }, 	1, ASN_TAG_CLASS_CONTEXT, 256, 1 },
+	{ 3, { 0xbf, 130, 1 }, 	1, ASN_TAG_CLASS_CONTEXT, 257, 1 },
+	{ 3, { 0xbf, 130, 0x81 }, 	0, 0, 0, 0 },
+	{ 4, { 0xbf, 130, 0x81, 2 }, 	1, ASN_TAG_CLASS_CONTEXT, 32898, 1 },
+	{ 4, { 0xbf, 130, 0x81, 0x82 }, 0, ASN_TAG_CLASS_CONTEXT, 32898, 1 },
+	{ 5, { 0x1f, 130, 0x81, 0x82, 1 }, 1, 0, 4210945, 0 },
+	{ 5, { 0x1f, 130, 0x81, 0x82, 2 }, 1, 0, 4210946, 0 },
+	{ 5, { 0x1f, 0xff, 0x81, 0x82, 2 }, 1, 0, 266354946, 0 },
+	{ 6, { 0x1f, 0xff, 0xff, 0x82, 0x80, 1 }, -1, 0, 266354946, 0 },
+	{ 7, { 0x1f, 0x8E, 0x87, 0xAA, 0x95, 0x99, 3}, -1, 0, 4000000000UL, 0 },
+};
+
+
+static void check_decode(struct tag_control_s *ctrl);
+static void check_encode(struct tag_control_s *ctrl);
+
+int
+main() {
+	size_t i;
+
+	for(i = 0; i < sizeof(control) / sizeof(control[0]); i++) {
+		check_decode(&control[i]);
+		check_encode(&control[i]);
+	}
+
+	return 0;
+}
+
+static void
+check_decode(struct tag_control_s *ctrl) {
+	ber_tlv_tag_t tag = 123;
+	ber_tlv_tag_t tag1 = 124;
+	ber_tlv_tag_t tag2 = 125;
+	ssize_t size;
+
+	if(ctrl->correctly_decodable < 1) {
+		size = ber_fetch_tag(ctrl->tagbuf, ctrl->taglen, &tag1);
+		assert(size == ctrl->correctly_decodable);
+		return;
+	}
+
+	printf("Expecting ");
+	tag = (ctrl->tvalue << 2) | ctrl->tclass;
+	ber_tlv_tag_fwrite(tag, stdout);
+	printf(", got ");
+
+	size = ber_fetch_tag(ctrl->tagbuf, 0, &tag1);
+	assert(size == 0);
+
+	size = ber_fetch_tag(ctrl->tagbuf, ctrl->taglen, &tag1);
+	assert(size == ctrl->taglen);
+
+	size = ber_fetch_tag(ctrl->tagbuf, ctrl->taglen + 10, &tag2);
+	assert(size == ctrl->taglen);
+
+	ber_tlv_tag_fwrite(tag1, stdout);
+	printf("\n");
+
+	assert(tag1 == tag2);
+	assert(tag == tag1);
+
+	assert(ctrl->constr == BER_TLV_CONSTRUCTED(ctrl->tagbuf));
+}
+
+
+
+static void
+check_encode(struct tag_control_s *ctrl) {
+	uint8_t buf[16];
+	ber_tlv_tag_t tag;
+	int Filler = 0xDA;
+	ssize_t size;
+	ssize_t i;
+
+	tag = ctrl->tvalue << 2 | ctrl->tclass;
+
+	/*
+	 * Testing buffer overruns.
+	 */
+	for(i = 0; i < (int)sizeof(buf); i++) {
+		int j;
+
+		memset(buf, Filler, sizeof(buf));
+
+		size = ber_tlv_tag_serialize(tag, buf, i);
+		assert(size < (int)sizeof(buf));
+
+		if(size <= i) {
+			for(j = 0; j < size; j++) assert(buf[j] != Filler);
+		} else {
+			j = i;
+		}
+		for(; j < (int)sizeof(buf); j++) assert(buf[j] == Filler);
+	}
+
+	memset(buf, Filler, sizeof(buf));
+
+	size = ber_tlv_tag_serialize(tag, buf, sizeof(buf));
+	assert(size < (int)sizeof(buf));
+
+	for(i = 0; i < size; i++) assert(buf[i] != Filler);
+	for(; i < (int)sizeof(buf); i++) assert(buf[i] == Filler);
+
+	if(ctrl->correctly_decodable == 1) {
+		assert(size == ctrl->taglen);
+	}
+	if(ctrl->constr) *buf |= 0x20;
+
+	ber_tlv_tag_fwrite(tag, stdout);
+
+	printf(":");
+
+	for(i = 0; i < size; i++) {
+		printf(" %02x", buf[i]);
+		if(ctrl->correctly_decodable == 1) {
+			assert(ctrl->tagbuf[i] == buf[i]);
+		}
+	}
+	printf("\n");
+}
+