diff --git a/wled00/json.cpp b/wled00/json.cpp
index 5fa4c04fe..6ac19189c 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -974,9 +974,10 @@ void serializeNodes(JsonObject root)
 // deserializes mode data string into JsonArray
 void serializeModeData(JsonArray fxdata)
 {
-  char lineBuffer[128];
+  char lineBuffer[256];
   for (size_t i = 0; i < strip.getModeCount(); i++) {
-    strncpy_P(lineBuffer, strip.getModeData(i), 127);
+    strncpy_P(lineBuffer, strip.getModeData(i), 255);
+    lineBuffer[255] = '\0'; // terminate string
     if (lineBuffer[0] != 0) {
       char* dataPtr = strchr(lineBuffer,'@');
       if (dataPtr) fxdata.add(dataPtr+1);
@@ -987,10 +988,12 @@ void serializeModeData(JsonArray fxdata)
 
 // deserializes mode names string into JsonArray
 // also removes effect data extensions (@...) from deserialised names
-void serializeModeNames(JsonArray arr) {
-  char lineBuffer[128];
+void serializeModeNames(JsonArray arr)
+{
+  char lineBuffer[256];
   for (size_t i = 0; i < strip.getModeCount(); i++) {
-    strncpy_P(lineBuffer, strip.getModeData(i), 127);
+    strncpy_P(lineBuffer, strip.getModeData(i), 255);
+    lineBuffer[255] = '\0'; // terminate string
     if (lineBuffer[0] != 0) {
       char* dataPtr = strchr(lineBuffer,'@');
       if (dataPtr) *dataPtr = 0; // terminate mode data after name
diff --git a/wled00/util.cpp b/wled00/util.cpp
index b8dea2555..220b4773b 100644
--- a/wled00/util.cpp
+++ b/wled00/util.cpp
@@ -233,7 +233,8 @@ uint8_t extractModeName(uint8_t mode, const char *src, char *dest, uint8_t maxLe
     if (mode < strip.getModeCount()) {
       char lineBuffer[256];
       //strcpy_P(lineBuffer, (const char*)pgm_read_dword(&(WS2812FX::_modeData[mode])));
-      strcpy_P(lineBuffer, strip.getModeData(mode));
+      strncpy_P(lineBuffer, strip.getModeData(mode), 255);
+      lineBuffer[255] = '\0'; // terminate string
       size_t len = strlen(lineBuffer);
       size_t j = 0;
       for (; j < maxLen && j < len; j++) {
@@ -355,9 +356,9 @@ uint8_t extractModeSlider(uint8_t mode, uint8_t slider, char *dest, uint8_t maxL
 int16_t extractModeDefaults(uint8_t mode, const char *segVar)
 {
   if (mode < strip.getModeCount()) {
-    char lineBuffer[128] = "";
-    strncpy_P(lineBuffer, strip.getModeData(mode), 127);
-    lineBuffer[127] = '\0'; // terminate string
+    char lineBuffer[256];
+    strncpy_P(lineBuffer, strip.getModeData(mode), 255);
+    lineBuffer[255] = '\0'; // terminate string
     if (lineBuffer[0] != 0) {
       char* startPtr = strrchr(lineBuffer, ';'); // last ";" in FX data
       if (!startPtr) return -1;