diff --git a/ports/stm32/boards/PYBD_SF2/mpconfigboard.mk b/ports/stm32/boards/PYBD_SF2/mpconfigboard.mk
index 9917aa2c57..6615a44a53 100644
--- a/ports/stm32/boards/PYBD_SF2/mpconfigboard.mk
+++ b/ports/stm32/boards/PYBD_SF2/mpconfigboard.mk
@@ -20,4 +20,4 @@ MICROPY_SSL_MBEDTLS = 1
 MICROPY_VFS_LFS2 = 1
 
 # PYBD-specific frozen modules
-FROZEN_MANIFEST = $(BOARD_DIR)/manifest.py
+FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest.py
diff --git a/ports/stm32/boards/PYBD_SF3/mpconfigboard.mk b/ports/stm32/boards/PYBD_SF3/mpconfigboard.mk
index 6bcc68f4b1..550094b743 100644
--- a/ports/stm32/boards/PYBD_SF3/mpconfigboard.mk
+++ b/ports/stm32/boards/PYBD_SF3/mpconfigboard.mk
@@ -20,4 +20,4 @@ MICROPY_SSL_MBEDTLS = 1
 MICROPY_VFS_LFS2 = 1
 
 # PYBD-specific frozen modules
-FROZEN_MANIFEST = boards/PYBD_SF2/manifest.py
+FROZEN_MANIFEST ?= boards/PYBD_SF2/manifest.py
diff --git a/ports/stm32/boards/PYBD_SF6/mpconfigboard.mk b/ports/stm32/boards/PYBD_SF6/mpconfigboard.mk
index bac516ab79..9db2210559 100644
--- a/ports/stm32/boards/PYBD_SF6/mpconfigboard.mk
+++ b/ports/stm32/boards/PYBD_SF6/mpconfigboard.mk
@@ -17,4 +17,4 @@ MICROPY_SSL_MBEDTLS = 1
 MICROPY_VFS_LFS2 = 1
 
 # PYBD-specific frozen modules
-FROZEN_MANIFEST = boards/PYBD_SF2/manifest.py
+FROZEN_MANIFEST ?= boards/PYBD_SF2/manifest.py