diff --git a/Engine/source/core/util/uuid.cpp b/Engine/source/core/util/uuid.cpp
index dfc578e11..d3cc1de87 100644
--- a/Engine/source/core/util/uuid.cpp
+++ b/Engine/source/core/util/uuid.cpp
@@ -146,7 +146,14 @@ static void create_uuid_state(uuid_state *st)
  */
 static void format_token(char *target, const xuuid_t *u)
 {
-   snprintf(target, strlen(target), "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+   // first loop, figure out the size needed.
+   size_t len = (size_t)snprintf(NULL, 0, "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+            u->time_low, u->time_mid, u->time_hi_and_version,
+            u->clock_seq_hi_and_reserved, u->clock_seq_low,
+            u->node[0], u->node[1], u->node[2],
+            u->node[3], u->node[4], u->node[5]);
+   
+   snprintf(target, len+1, "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
             u->time_low, u->time_mid, u->time_hi_and_version,
             u->clock_seq_hi_and_reserved, u->clock_seq_low,
             u->node[0], u->node[1], u->node[2],