diff --git a/wled00/util.cpp b/wled00/util.cpp
index 8c8ff7256..914f09ee3 100644
--- a/wled00/util.cpp
+++ b/wled00/util.cpp
@@ -148,7 +148,7 @@ bool oappendi(int i)
 bool oappend(const char* txt)
 {
   uint16_t len = strlen(txt);
-  if (olen + len >= SETTINGS_STACK_BUF_SIZE) {
+  if ((obuf == nullptr) || (olen + len >= SETTINGS_STACK_BUF_SIZE)) { // sanity checks
 #ifdef WLED_DEBUG
     DEBUG_PRINT(F("oappend() buffer overflow. Cannot append "));
     DEBUG_PRINT(len); DEBUG_PRINT(F(" bytes \t\""));