diff --git a/builder/frameworks/base.py b/builder/frameworks/base.py
index e7ef82d..c9b3b71 100644
--- a/builder/frameworks/base.py
+++ b/builder/frameworks/base.py
@@ -16,6 +16,8 @@ family: Family = env["FAMILY_OBJ"]
 
 # Parse custom options
 env.ParseCustomOptions(platform)
+# Parse custom flash layout
+env.ParseCustomFlashLayout(platform, board)
 # Add flash layout C defines
 env.AddFlashLayout(board)
 # Write custom header options
@@ -23,7 +25,7 @@ env.ApplyCustomOptions(platform)
 # Export board manifest for ltchiptool
 env.ExportBoardData(board)
 # Print information about versions and custom options
-env.PrintInfo(platform)
+env.PrintInfo(platform, board)
 
 # TODO remove include path prepending ("!<...>")
 # Move common core sources (env.AddCoreSources()) and Arduino libs
diff --git a/builder/utils/env.py b/builder/utils/env.py
index 700ebc1..c9f53a4 100644
--- a/builder/utils/env.py
+++ b/builder/utils/env.py
@@ -89,7 +89,11 @@ def env_configure(
     return family
 
 
-def env_print_info(env: Environment, platform: PlatformBase):
+def env_print_info(
+    env: Environment,
+    platform: PlatformBase,
+    board: PlatformBoardConfig,
+):
     TAB = " " * 4
 
     def dump(k, v, indent=""):
@@ -114,10 +118,15 @@ def env_print_info(env: Environment, platform: PlatformBase):
         print("CUSTOM OPTIONS:")
         for k, v in sorted(platform.custom_opts.items()):
             dump(k, v)
+    # Print custom flash layout
+    if env.get("FLASH_IS_CUSTOM", False):
+        print("CUSTOM FLASH LAYOUT:")
+        for k, v in board.get("flash").items():
+            print(f" - {k}: {v}")
 
 
 def env_parse_custom_options(env: Environment, platform: PlatformBase):
-    opts = platform.custom_opts.get("options", None)
+    opts: dict = platform.custom_opts.get("options", None)
     if not opts:
         return
     headers = {
diff --git a/builder/utils/flash.py b/builder/utils/flash.py
index b28c0a7..af521e5 100644
--- a/builder/utils/flash.py
+++ b/builder/utils/flash.py
@@ -2,14 +2,52 @@
 
 import re
 from os.path import isfile, join
+from typing import Dict
 
 from ltchiptool.util.fileio import chext
+from platformio.platform.base import PlatformBase
 from platformio.platform.board import PlatformBoardConfig
 from SCons.Script import DefaultEnvironment, Environment
 
 env: Environment = DefaultEnvironment()
 
 
+def env_parse_custom_flash_layout(
+    env: Environment,
+    platform: PlatformBase,
+    board: PlatformBoardConfig,
+):
+    opts: dict = platform.custom_opts.get("flash", None)
+    if not opts:
+        return
+    flash_layout: dict = board.get("flash")
+
+    # find all default partitions
+    partitions: Dict[str, int] = {}
+    flash_size = 0
+    for name, layout in flash_layout.items():
+        (offset, _, length) = layout.partition("+")
+        offset = int(offset, 16)
+        length = int(length, 16)
+        partitions[name] = offset
+        flash_size = max(flash_size, offset + length)
+
+    # set custom offsets
+    for name, offset in opts.items():
+        offset = int(offset, 0)
+        partitions[name] = offset
+
+    # recalculate partition sizes
+    flash_layout = {}
+    partitions = sorted(partitions.items(), key=lambda p: p[1])
+    for i, (name, offset) in enumerate(partitions):
+        end = partitions[i + 1][1] if i + 1 < len(partitions) else flash_size
+        length = end - offset
+        flash_layout[name] = f"0x{offset:06X}+0x{length:X}"
+    board.manifest["flash"] = flash_layout
+    env["FLASH_IS_CUSTOM"] = True
+
+
 def env_add_flash_layout(env: Environment, board: PlatformBoardConfig):
     flash_layout: dict = board.get("flash")
     if flash_layout:
@@ -74,5 +112,6 @@ def env_generate_linker_script(env: Environment, board: PlatformBoardConfig, nam
     env.Prepend(LIBPATH=["${BUILD_DIR}"])
 
 
+env.AddMethod(env_parse_custom_flash_layout, "ParseCustomFlashLayout")
 env.AddMethod(env_add_flash_layout, "AddFlashLayout")
 env.AddMethod(env_generate_linker_script, "GenerateLinkerScript")