diff --git a/lib/util/util_str_hex.c b/lib/util/util_str_hex.c
index 792b4e8420b..553fb30681e 100644
--- a/lib/util/util_str_hex.c
+++ b/lib/util/util_str_hex.c
@@ -1,48 +1,27 @@
 #include "replace.h"
-#include "libcli/util/ntstatus.h"
 #include "util_str_hex.h"
+#include "lib/util/data_blob.h"
+#include "librpc/gen_ndr/misc.h"
 
-NTSTATUS read_hex_bytes(const char *s, uint hexchars, uint64_t *dest)
+static bool hex_uint16(const char *in, uint16_t *out)
 {
-	uint64_t x = 0;
-	uint i;
-	char c;
-
-	if ((hexchars & 1) || hexchars > 16) {
-		return NT_STATUS_INVALID_PARAMETER;
-	}
-
-	for (i = 0; i < hexchars; i++) {
-		x <<= 4;
-		c = s[i];
-		if (c >= '0' && c <= '9') {
-			x += c - '0';
-		}
-		else if (c >= 'a' && c <= 'f') {
-			x += c - 'a' + 10;
-		}
-		else if (c >= 'A' && c <= 'F') {
-			x += c - 'A' + 10;
-		}
-		else {
-			/* BAD character (including '\0') */
-			return NT_STATUS_INVALID_PARAMETER;
-		}
-	}
-	*dest = x;
-	return NT_STATUS_OK;
+	uint8_t hi=0, lo=0;
+	bool ok = hex_byte(in, &hi) && hex_byte(in+2, &lo);
+	*out = (((uint16_t)hi)<<8) + lo;
+	return ok;
 }
 
-
-NTSTATUS parse_guid_string(const char *s,
-			   uint32_t *time_low,
-			   uint32_t *time_mid,
-			   uint32_t *time_hi_and_version,
-			   uint32_t clock_seq[2],
-			   uint32_t node[6])
+bool hex_uint32(const char *in, uint32_t *out)
 {
-	uint64_t tmp;
-	NTSTATUS status;
+	uint16_t hi=0, lo=0;
+	bool ok = hex_uint16(in, &hi) && hex_uint16(in+4, &lo);
+	*out = (((uint32_t)hi)<<16) + lo;
+	return ok;
+}
+
+bool parse_guid_string(const char *s, struct GUID *guid)
+{
+	bool ok;
 	int i;
 	/* "e12b56b6-0a95-11d1-adbb-00c04fd8d5cd"
                 |     |    |    |    |
@@ -52,49 +31,39 @@ NTSTATUS parse_guid_string(const char *s,
 		|     \_______________ time_mid
 		\_____________________ time_low
 	*/
-	status = read_hex_bytes(s, 8, &tmp);
-	if (!NT_STATUS_IS_OK(status) || s[8] != '-') {
-		return NT_STATUS_INVALID_PARAMETER;
+
+	ok = hex_uint32(s, &guid->time_low);
+	if (!ok || (s[8] != '-')) {
+		return false;
 	}
-	*time_low = tmp;
 	s += 9;
 
-	status = read_hex_bytes(s, 4, &tmp);
-	if (!NT_STATUS_IS_OK(status) || s[4] != '-') {
-		return NT_STATUS_INVALID_PARAMETER;
+	ok = hex_uint16(s, &guid->time_mid);
+	if (!ok || (s[4] != '-')) {
+		return false;
 	}
-	*time_mid = tmp;
 	s += 5;
 
-	status = read_hex_bytes(s, 4, &tmp);
-	if (!NT_STATUS_IS_OK(status) || s[4] != '-') {
-		return NT_STATUS_INVALID_PARAMETER;
+	ok = hex_uint16(s, &guid->time_hi_and_version);
+	if (!ok || (s[4] != '-')) {
+		return false;
 	}
-	*time_hi_and_version = tmp;
 	s += 5;
 
-	for (i = 0; i < 2; i++) {
-		status = read_hex_bytes(s, 2, &tmp);
-		if (!NT_STATUS_IS_OK(status)) {
-			return NT_STATUS_INVALID_PARAMETER;
-		}
-		clock_seq[i] = tmp;
-		s += 2;
+	ok = hex_byte(s, &guid->clock_seq[0]) &&
+		hex_byte(s+2, &guid->clock_seq[1]);
+	if (!ok || (s[4] != '-')) {
+		return false;
 	}
-	if (s[0] != '-') {
-		return NT_STATUS_INVALID_PARAMETER;
-	}
-
-	s++;
+	s += 5;
 
 	for (i = 0; i < 6; i++) {
-		status = read_hex_bytes(s, 2, &tmp);
-		if (!NT_STATUS_IS_OK(status)) {
-			return NT_STATUS_INVALID_PARAMETER;
+		ok = hex_byte(s, &guid->node[i]);
+		if (!ok) {
+			return false;
 		}
-		node[i] = tmp;
 		s += 2;
 	}
 
-	return NT_STATUS_OK;
+	return true;
 }
diff --git a/lib/util/util_str_hex.h b/lib/util/util_str_hex.h
index d0d53e3ed05..7dd527fcdab 100644
--- a/lib/util/util_str_hex.h
+++ b/lib/util/util_str_hex.h
@@ -1,10 +1,5 @@
-#include "../libcli/util/ntstatus.h"
+#include "replace.h"
 
-NTSTATUS read_hex_bytes(const char *s, uint hexchars, uint64_t *dest);
-
-NTSTATUS parse_guid_string(const char *s,
-			   uint32_t *time_low,
-			   uint32_t *time_mid,
-			   uint32_t *time_hi_and_version,
-			   uint32_t clock_seq[2],
-			   uint32_t node[6]);
+bool hex_uint32(const char *in, uint32_t *out);
+struct GUID;
+bool parse_guid_string(const char *s, struct GUID *guid);
diff --git a/librpc/ndr/ndr_misc.c b/librpc/ndr/ndr_misc.c
index 12c853e387c..d7ebb066b8a 100644
--- a/librpc/ndr/ndr_misc.c
+++ b/librpc/ndr/ndr_misc.c
@@ -61,22 +61,10 @@ _PUBLIC_ char *ndr_syntax_id_to_string(TALLOC_CTX *mem_ctx, const struct ndr_syn
 
 _PUBLIC_ bool ndr_syntax_id_from_string(const char *s, struct ndr_syntax_id *id)
 {
-	size_t i;
-	uint32_t time_low;
-	uint32_t time_mid, time_hi_and_version;
-	uint32_t clock_seq[2];
-	uint32_t node[6];
-	uint64_t if_version;
-	NTSTATUS status;
+	bool ok;
 
-	status =  parse_guid_string(s,
-				    &time_low,
-				    &time_mid,
-				    &time_hi_and_version,
-				    clock_seq,
-				    node);
-
-	if (!NT_STATUS_IS_OK(status)) {
+	ok =  parse_guid_string(s, &id->uuid);
+	if (!ok) {
 		return false;
 	}
 
@@ -84,21 +72,6 @@ _PUBLIC_ bool ndr_syntax_id_from_string(const char *s, struct ndr_syntax_id *id)
 		return false;
 	}
 
-	status = read_hex_bytes(s + 39, 8, &if_version);
-
-	if (!NT_STATUS_IS_OK(status)) {
-		return false;
-	}
-
-	id->uuid.time_low = time_low;
-	id->uuid.time_mid = time_mid;
-	id->uuid.time_hi_and_version = time_hi_and_version;
-	id->uuid.clock_seq[0] = clock_seq[0];
-	id->uuid.clock_seq[1] = clock_seq[1];
-	for (i=0; i<6; i++) {
-		id->uuid.node[i] = node[i];
-	}
-	id->if_version = (uint32_t)if_version;
-
-	return true;
+	ok = hex_uint32(s+39, &id->if_version);
+	return ok;
 }
diff --git a/librpc/ndr/uuid.c b/librpc/ndr/uuid.c
index ad5c9d37d11..2c16f5ad81c 100644
--- a/librpc/ndr/uuid.c
+++ b/librpc/ndr/uuid.c
@@ -77,78 +77,42 @@ _PUBLIC_ NTSTATUS GUID_from_ndr_blob(const DATA_BLOB *b, struct GUID *guid)
 */
 _PUBLIC_ NTSTATUS GUID_from_data_blob(const DATA_BLOB *s, struct GUID *guid)
 {
-	NTSTATUS status = NT_STATUS_INVALID_PARAMETER;
-	uint32_t time_low = 0;
-	uint32_t time_mid = 0;
-	uint32_t time_hi_and_version = 0;
-	uint32_t clock_seq[2] = {0};
-	uint32_t node[6] = {0};
-	uint8_t buf16[16] = {0};
-
-	DATA_BLOB blob16 = data_blob_const(buf16, sizeof(buf16));
-	int i;
+	bool ok;
 
 	if (s->data == NULL) {
 		return NT_STATUS_INVALID_PARAMETER;
 	}
 
-	switch(s->length) {
-	case 36:
-	{
-		status = parse_guid_string((char *)s->data,
-					   &time_low,
-					   &time_mid,
-					   &time_hi_and_version,
-					   clock_seq,
-					   node);
-		break;
+	if (s->length == 36) {
+		ok = parse_guid_string((char *)s->data, guid);
+		return ok ? NT_STATUS_OK : NT_STATUS_INVALID_PARAMETER;
 	}
-	case 38:
-	{
-		if (s->data[0] != '{' || s->data[37] != '}') {
-			break;
-		}
 
-		status = parse_guid_string((char *)s->data + 1,
-					   &time_low,
-					   &time_mid,
-					   &time_hi_and_version,
-					   clock_seq,
-					   node);
-		break;
+	if (s->length == 38) {
+		if (s->data[0] != '{' || s->data[37] != '}') {
+			return NT_STATUS_INVALID_PARAMETER;
+		}
+		ok = parse_guid_string((char *)s->data + 1, guid);
+		return ok ? NT_STATUS_OK : NT_STATUS_INVALID_PARAMETER;
 	}
-	case 32:
-	{
+
+	if (s->length == 32) {
+		uint8_t buf16[16] = {0};
+		DATA_BLOB blob16 = { .data = buf16, .length = sizeof(buf16) };
 		size_t rlen = strhex_to_str((char *)blob16.data, blob16.length,
 					    (const char *)s->data, s->length);
 		if (rlen != blob16.length) {
 			return NT_STATUS_INVALID_PARAMETER;
 		}
 
-		s = &blob16;
+		return GUID_from_ndr_blob(&blob16, guid);
+	}
+
+	if (s->length == 16) {
 		return GUID_from_ndr_blob(s, guid);
 	}
-	case 16:
-		return GUID_from_ndr_blob(s, guid);
-	default:
-		status = NT_STATUS_INVALID_PARAMETER;
-		break;
-	}
 
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
-	}
-
-	guid->time_low = time_low;
-	guid->time_mid = time_mid;
-	guid->time_hi_and_version = time_hi_and_version;
-	guid->clock_seq[0] = clock_seq[0];
-	guid->clock_seq[1] = clock_seq[1];
-	for (i=0;i<6;i++) {
-		guid->node[i] = node[i];
-	}
-
-	return NT_STATUS_OK;
+	return NT_STATUS_INVALID_PARAMETER;
 }
 
 /**