diff --git a/src/util-debug.c b/src/util-debug.c
index 8283c99c5f..7a78987dda 100644
--- a/src/util-debug.c
+++ b/src/util-debug.c
@@ -358,12 +358,19 @@ SCError SCLogMessage(SCLogLevel log_level, char **msg, const char *file,
                 substr = temp_fmt;
                 substr++;
                 break;
-
             case SC_LOG_FMT_TM:
                 temp_fmt[0] = '\0';
+/* disabled to prevent dead lock:
+ * log or alloc (which calls log on error) can call TmThreadsGetCallingThread
+ * which will lock tv_root_lock. This can happen while we already hold this
+ * lock. */
+#if 0
                 ThreadVars *tv = TmThreadsGetCallingThread();
                 cw = snprintf(temp, SC_LOG_MAX_LOG_MSG_LEN - (temp - *msg),
                               "%s%s", substr, ((tv != NULL)? tv->name: "UNKNOWN TM"));
+#endif
+                cw = snprintf(temp, SC_LOG_MAX_LOG_MSG_LEN - (temp - *msg),
+                              "%s%s", substr, "N/A");
                 if (cw < 0)
                     goto error;
                 temp += cw;
@@ -371,7 +378,6 @@ SCError SCLogMessage(SCLogLevel log_level, char **msg, const char *file,
                 substr = temp_fmt;
                 substr++;
                 break;
-
             case SC_LOG_FMT_LOG_LEVEL:
                 temp_fmt[0] = '\0';
                 s = SCMapEnumValueToName(log_level, sc_log_level_map);