diff --git a/ports/broadcom/Makefile b/ports/broadcom/Makefile
index 757e7f3450..ca516958e0 100644
--- a/ports/broadcom/Makefile
+++ b/ports/broadcom/Makefile
@@ -1,11 +1,18 @@
 # Select the board to build for.
-BOARD?=raspberrypi_pi4b
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
 
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD "$(BOARD)" specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/cxd56/Makefile b/ports/cxd56/Makefile
index 073d2d59ce..208d3222b0 100644
--- a/ports/cxd56/Makefile
+++ b/ports/cxd56/Makefile
@@ -23,11 +23,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/espressif/Makefile b/ports/espressif/Makefile
index 30c35f9caf..331e443561 100644
--- a/ports/espressif/Makefile
+++ b/ports/espressif/Makefile
@@ -23,11 +23,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/litex/Makefile b/ports/litex/Makefile
index 6b1e33c8d1..3281977657 100644
--- a/ports/litex/Makefile
+++ b/ports/litex/Makefile
@@ -23,11 +23,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/mimxrt10xx/Makefile b/ports/mimxrt10xx/Makefile
index 4b05c91714..2dda646882 100644
--- a/ports/mimxrt10xx/Makefile
+++ b/ports/mimxrt10xx/Makefile
@@ -24,11 +24,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/nrf/Makefile b/ports/nrf/Makefile
index bbe102ffc8..2dbc582022 100755
--- a/ports/nrf/Makefile
+++ b/ports/nrf/Makefile
@@ -23,14 +23,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(info You must provide a BOARD parameter with 'BOARD=')
-  $(info Possible values are:)
-  $(info $(sort $(subst /.,,$(subst boards/,,$(wildcard boards/*/.)))))
-  $(error BOARD not defined)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/raspberrypi/Makefile b/ports/raspberrypi/Makefile
index 5095c4c1f8..151c60ba1b 100644
--- a/ports/raspberrypi/Makefile
+++ b/ports/raspberrypi/Makefile
@@ -23,11 +23,20 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-  $(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
   ifeq ($(wildcard boards/$(BOARD)/.),)
-    $(error Invalid BOARD specified)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
   endif
 endif
 
diff --git a/ports/stm/Makefile b/ports/stm/Makefile
index afde51bdc0..ac373cbbfa 100755
--- a/ports/stm/Makefile
+++ b/ports/stm/Makefile
@@ -24,12 +24,21 @@
 # THE SOFTWARE.
 
 # Select the board to build for.
+define show_board_error
+boardlist =
+$(info Valid boards:)
+$(shell printf '%s\n' $(patsubst boards/%/mpconfigboard.mk,%,$(wildcard boards/*/mpconfigboard.mk)) | column -xc $$(tput cols || echo 80) 1>&2)
+$(error Rerun with $(MAKE) BOARD=<board>)
+endef
+
 ifeq ($(BOARD),)
-$(error You must provide a BOARD parameter)
+    $(info No BOARD specified)
+    $(call show_board_error)
 else
-ifeq ($(wildcard boards/$(BOARD)/.),)
-$(error Invalid BOARD specified)
-endif
+  ifeq ($(wildcard boards/$(BOARD)/.),)
+    $(info Invalid BOARD specified)
+    $(call show_board_error)
+  endif
 endif
 
 # If the build directory is not given, make it reflect the board name.