diff --git a/builder/utils/env.py b/builder/utils/env.py
index 1453664c3..721c6f725 100644
--- a/builder/utils/env.py
+++ b/builder/utils/env.py
@@ -126,7 +126,7 @@ def dump(k, v, indent=""):
     if env.get("FLASH_IS_CUSTOM", False):
         print("CUSTOM FLASH LAYOUT:")
         for name, layout in board.get("flash").items():
-            (_, _, length) = v.partition("+")
+            (_, _, length) = layout.partition("+")
             length = int(length, 16)
             print(f" - {name}: {layout} ({sizeof(length)})")