Index: include/lldb/Utility/UUID.h
===================================================================
--- include/lldb/Utility/UUID.h
+++ include/lldb/Utility/UUID.h
@@ -85,7 +85,7 @@
   //------------------------------------------------------------------
   // Classes that inherit from UUID can see and modify these
   //------------------------------------------------------------------
-  uint32_t m_num_uuid_bytes; // Should be 16 or 20
+  uint32_t m_num_uuid_bytes;
   ValueType m_uuid;
 };
 
Index: source/Utility/UUID.cpp
===================================================================
--- source/Utility/UUID.cpp
+++ source/Utility/UUID.cpp
@@ -56,22 +56,26 @@
   char buf[256];
   if (!separator)
     separator = "-";
-  const uint8_t *u = (const uint8_t *)GetBytes();
-  if (sizeof(buf) >
-      (size_t)snprintf(buf, sizeof(buf), "%2.2X%2.2X%2.2X%2.2X%s%2.2X%2.2X%s%2."
-                                         "2X%2.2X%s%2.2X%2.2X%s%2.2X%2.2X%2.2X%"
-                                         "2.2X%2.2X%2.2X",
-                       u[0], u[1], u[2], u[3], separator, u[4], u[5], separator,
-                       u[6], u[7], separator, u[8], u[9], separator, u[10],
-                       u[11], u[12], u[13], u[14], u[15])) {
+  auto u = reinterpret_cast<const uint8_t *>(GetBytes());
+  int required_bytes;
+
+  required_bytes =
+      snprintf(buf, sizeof(buf),
+               "%2.2X%2.2X%2.2X%2.2X%s%2.2X%2.2X%s%2.2X%2.2X%s"
+               "%2.2X%2.2X%s%2.2X%2.2X%2.2X%2.2X%2.2X%2.2X",
+               u[0], u[1], u[2], u[3], separator, u[4], u[5], separator, u[6],
+               u[7], separator, u[8], u[9], separator, u[10], u[11], u[12],
+               u[13], u[14], u[15]);
+  assert(required_bytes < sizeof(buf));
+  result.append(buf);
+
+  if (m_num_uuid_bytes > 16) {
+    required_bytes = snprintf(buf, sizeof(buf), "%s%2.2X%2.2X%2.2X%2.2X",
+                              separator, u[16], u[17], u[18], u[19]);
+    assert(required_bytes < sizeof(buf));
     result.append(buf);
-    if (m_num_uuid_bytes == 20) {
-      if (sizeof(buf) > (size_t)snprintf(buf, sizeof(buf),
-                                         "%s%2.2X%2.2X%2.2X%2.2X", separator,
-                                         u[16], u[17], u[18], u[19]))
-        result.append(buf);
-    }
   }
+
   return result;
 }
 
@@ -80,28 +84,16 @@
 }
 
 bool UUID::SetBytes(const void *uuid_bytes, uint32_t num_uuid_bytes) {
-  if (uuid_bytes) {
-    switch (num_uuid_bytes) {
-    case 20:
-      m_num_uuid_bytes = 20;
-      break;
-    case 16:
-      m_num_uuid_bytes = 16;
-      m_uuid[16] = m_uuid[17] = m_uuid[18] = m_uuid[19] = 0;
-      break;
-    default:
-      // Unsupported UUID byte size
-      m_num_uuid_bytes = 0;
-      break;
-    }
-
-    if (m_num_uuid_bytes > 0) {
-      ::memcpy(m_uuid, uuid_bytes, m_num_uuid_bytes);
-      return true;
-    }
+  if (uuid_bytes == nullptr || num_uuid_bytes == 0) {
+    m_num_uuid_bytes = 0;
+    return false;
   }
-  ::memset(m_uuid, 0, sizeof(m_uuid));
-  return false;
+
+  m_num_uuid_bytes = num_uuid_bytes;
+  ::memcpy(m_uuid, uuid_bytes, m_num_uuid_bytes);
+  ::memset(m_uuid + num_uuid_bytes, 0, sizeof(m_uuid) - m_num_uuid_bytes);
+
+  return true;
 }
 
 size_t UUID::GetByteSize() const { return m_num_uuid_bytes; }