diff --git a/wled00/FX.h b/wled00/FX.h
index 9fd3a04d8a..3aeca57124 100644
--- a/wled00/FX.h
+++ b/wled00/FX.h
@@ -879,6 +879,7 @@ class WS2812FX {
       printSize(),                                // prints memory usage for strip components
 #endif
       finalizeInit(),                             // initialises strip components
+      updatePixelBuffer(),                        // (re)allocate memory for _pixels[]
       service(),                                  // executes effect functions when due and calls strip.show()
       setCCT(uint16_t k),                         // sets global CCT (either in relative 0-255 value or in K)
       setBrightness(uint8_t b, bool direct = false),    // sets strip brightness
diff --git a/wled00/FX_fcn.cpp b/wled00/FX_fcn.cpp
index 452cb91764..69a6152c01 100644
--- a/wled00/FX_fcn.cpp
+++ b/wled00/FX_fcn.cpp
@@ -1272,11 +1272,17 @@ void WS2812FX::finalizeInit() {
   deserializeMap();     // (re)load default ledmap (will also setUpMatrix() if ledmap does not exist)
 
   // allocate frame buffer after matrix has been set up (gaps!)
+  updatePixelBuffer();
+  DEBUG_PRINTF_P(PSTR("Heap after strip init: %uB\n"), getFreeHeapSize());
+}
+
+// update global _pixels[] buffer to match getLengthTotal() note: if allocation fails, WLED will not render anything
+void WS2812FX::updatePixelBuffer() {
+  uint32_t requiredMem = getLengthTotal() * sizeof(uint32_t);
   p_free(_pixels); // using realloc on large buffers can cause additional fragmentation instead of reducing it
   // use PSRAM if available: there is no measurable perfomance impact between PSRAM and DRAM on S2/S3 with QSPI PSRAM for this buffer
-  _pixels = static_cast<uint32_t*>(allocate_buffer(getLengthTotal() * sizeof(uint32_t), BFRALLOC_ENFORCE_PSRAM | BFRALLOC_NOBYTEACCESS | BFRALLOC_CLEAR));
-  DEBUG_PRINTF_P(PSTR("strip buffer size: %uB\n"), getLengthTotal() * sizeof(uint32_t));
-  DEBUG_PRINTF_P(PSTR("Heap after strip init: %uB\n"), getFreeHeapSize());
+  _pixels = static_cast<uint32_t*>(allocate_buffer(requiredMem, BFRALLOC_ENFORCE_PSRAM | BFRALLOC_NOBYTEACCESS | BFRALLOC_CLEAR));
+  DEBUG_PRINTF_P(PSTR("strip buffer size: %uB\n"), requiredMem);
 }
 
 void WS2812FX::service() {
@@ -2080,10 +2086,13 @@ bool WS2812FX::deserializeMap(unsigned n) {
   customMappingSize = 0; // prevent use of mapping if anything goes wrong
   currentLedmap = 0;
   if (n == 0 || isFile) interfaceUpdateCallMode = CALL_MODE_WS_SEND; // schedule WS update (to inform UI)
+  uint32_t lengthTotalBefore = strip.getLengthTotal();
 
   if (!isFile && n==0 && isMatrix) {
     // 2D panel support creates its own ledmap (on the fly) if a ledmap.json does not exist
     setUpMatrix();
+    if (strip.getLengthTotal() != lengthTotalBefore)
+      strip.updatePixelBuffer(); // allocate _pixels[] to match new length
     return false;
   }
 
@@ -2158,6 +2167,8 @@ bool WS2812FX::deserializeMap(unsigned n) {
   }
 
   releaseJSONBufferLock();
+  if (strip.getLengthTotal() != lengthTotalBefore)
+    strip.updatePixelBuffer(); // allocate _pixels[] to match new length
   return (customMappingSize > 0);
 }