diff --git a/examples/companion_radio/ui-new/DiagnosticsScreen.h b/examples/companion_radio/ui-new/DiagnosticsScreen.h
index 7cdc89cd..b1cdb8a4 100644
--- a/examples/companion_radio/ui-new/DiagnosticsScreen.h
+++ b/examples/companion_radio/ui-new/DiagnosticsScreen.h
@@ -110,6 +110,8 @@ class DiagnosticsScreen : public UIScreen {
       if (err & ERR_EVENT_FULL)            strcat(buf, "F ");
       if (err & ERR_EVENT_CAD_TIMEOUT)     strcat(buf, "C ");
       if (err & ERR_EVENT_STARTRX_TIMEOUT) strcat(buf, "R ");
+      int len = strlen(buf);   // drop the trailing space so right-alignment sits flush
+      if (len > 0 && buf[len - 1] == ' ') buf[len - 1] = '\0';
     }
     addRow("Errors", buf);
   }
diff --git a/src/helpers/DeviceDiag.cpp b/src/helpers/DeviceDiag.cpp
index bfee9186..117dd72d 100644
--- a/src/helpers/DeviceDiag.cpp
+++ b/src/helpers/DeviceDiag.cpp
@@ -3,17 +3,20 @@
 #if defined(NRF52_PLATFORM)
 #include "FreeRTOS.h"
 #include "task.h"
+#include <malloc.h>
 
-// Same linker symbols + _sbrk() the core's own new.cpp uses to implement
-// malloc's heap (see framework-arduinoadafruitnrf52/cores/nRF5/new.cpp) —
-// there's no separate "free heap" API on this core, so this mirrors it.
-extern "C" char* _sbrk(int incr);
+// Heap region size from the linker symbols the core's new.cpp uses for sbrk
+// (framework-arduinoadafruitnrf52/cores/nRF5/new.cpp). "Used" comes from
+// newlib's mallinfo().uordblks (bytes actually outstanding) rather than
+// sbrk(0) - __HeapBase: sbrk only ever grows, so a high-water mark there
+// counts freed-and-recycled blocks as permanently "used" and free heap looks
+// far lower than it really is.
 extern unsigned char __HeapBase[];
 extern unsigned char __HeapLimit[];
 
 void DeviceDiag::getHeapStats(uint32_t& free_bytes, uint32_t& total_bytes) {
   total_bytes = (uint32_t)(__HeapLimit - __HeapBase);
-  uint32_t used = (uint32_t)((unsigned char*)_sbrk(0) - __HeapBase);
+  uint32_t used = (uint32_t)mallinfo().uordblks;
   free_bytes = (used < total_bytes) ? (total_bytes - used) : 0;
 }