diff --git a/stmhal/Makefile b/stmhal/Makefile
index d56125faf..64c58151b 100644
--- a/stmhal/Makefile
+++ b/stmhal/Makefile
@@ -224,12 +224,12 @@ $(BUILD)/firmware.elf: $(OBJ)
 
 MAKE_PINS = boards/make-pins.py
 BOARD_PINS = boards/$(BOARD)/pins.csv
-AF_FILE = boards/stm32f4xx-af.csv
-PREFIX_FILE = boards/stm32f4xx-prefix.c
+AF_FILE = boards/stm32f4xx_af.csv
+PREFIX_FILE = boards/stm32f4xx_prefix.c
 GEN_PINS_SRC = $(BUILD)/pins_$(BOARD).c
 GEN_PINS_HDR = $(HEADER_BUILD)/pins.h
 GEN_PINS_QSTR = $(BUILD)/pins_qstr.h
-GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins-af-const.h
+GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins_af_const.h
 
 INSERT_USB_IDS = ../tools/insert-usb-ids.py
 FILE2H = ../tools/file2h.py
@@ -250,7 +250,7 @@ $(BUILD)/main.o: $(GEN_CDCINF_HEADER)
 
 # Use a pattern rule here so that make will only call make-pins.py once to make
 # both pins_$(BOARD).c and pins.h
-$(BUILD)/%_$(BOARD).c $(HEADER_BUILD)/%.h $(HEADER_BUILD)/%-af-const.h $(BUILD)/%_qstr.h: boards/$(BOARD)/%.csv $(MAKE_PINS) $(AF_FILE) $(PREFIX_FILE) | $(HEADER_BUILD)
+$(BUILD)/%_$(BOARD).c $(HEADER_BUILD)/%.h $(HEADER_BUILD)/%_af_const.h $(BUILD)/%_qstr.h: boards/$(BOARD)/%.csv $(MAKE_PINS) $(AF_FILE) $(PREFIX_FILE) | $(HEADER_BUILD)
 	$(ECHO) "Create $@"
 	$(Q)$(PYTHON) $(MAKE_PINS) --board $(BOARD_PINS) --af $(AF_FILE) --prefix $(PREFIX_FILE) --hdr $(GEN_PINS_HDR) --qstr $(GEN_PINS_QSTR) --af-const $(GEN_PINS_AF_CONST) > $(GEN_PINS_SRC)
 
diff --git a/stmhal/boards/make-pins.py b/stmhal/boards/make-pins.py
index f3d1dee48..cc580f7cd 100755
--- a/stmhal/boards/make-pins.py
+++ b/stmhal/boards/make-pins.py
@@ -326,13 +326,13 @@ def main():
         "-a", "--af",
         dest="af_filename",
         help="Specifies the alternate function file for the chip",
-        default="stm32f4xx-af.csv"
+        default="stm32f4xx_af.csv"
     )
     parser.add_argument(
         "--af-const",
         dest="af_const_filename",
         help="Specifies header file for alternate function constants.",
-        default="build/pins-af-const.h"
+        default="build/pins_af_const.h"
     )
     parser.add_argument(
         "-b", "--board",
@@ -343,13 +343,13 @@ def main():
         "-p", "--prefix",
         dest="prefix_filename",
         help="Specifies beginning portion of generated pins file",
-        default="stm32f4xx-prefix.c"
+        default="stm32f4xx_prefix.c"
     )
     parser.add_argument(
         "-q", "--qstr",
         dest="qstr_filename",
         help="Specifies name of generated qstr header file",
-        default="build/pins-qstr.h"
+        default="build/pins_qstr.h"
     )
     parser.add_argument(
         "-r", "--hdr",
diff --git a/stmhal/boards/stm32f4xx-af.csv b/stmhal/boards/stm32f4xx_af.csv
similarity index 100%
rename from stmhal/boards/stm32f4xx-af.csv
rename to stmhal/boards/stm32f4xx_af.csv
diff --git a/stmhal/boards/stm32f4xx-prefix.c b/stmhal/boards/stm32f4xx_prefix.c
similarity index 91%
rename from stmhal/boards/stm32f4xx-prefix.c
rename to stmhal/boards/stm32f4xx_prefix.c
index 45bcc0b65..c20030172 100644
--- a/stmhal/boards/stm32f4xx-prefix.c
+++ b/stmhal/boards/stm32f4xx_prefix.c
@@ -1,4 +1,4 @@
-// stm32fxx-prefix.c becomes the initial portion of the generated pins file.
+// stm32f4xx_prefix.c becomes the initial portion of the generated pins file.
 
 #include <stdio.h>
 #include <stdint.h>
diff --git a/stmhal/pin.c b/stmhal/pin.c
index dbc0b5f14..0271ced30 100644
--- a/stmhal/pin.c
+++ b/stmhal/pin.c
@@ -534,7 +534,7 @@ STATIC const mp_map_elem_t pin_locals_dict_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_PULL_UP),   MP_OBJ_NEW_SMALL_INT(GPIO_PULLUP) },
     { MP_OBJ_NEW_QSTR(MP_QSTR_PULL_DOWN), MP_OBJ_NEW_SMALL_INT(GPIO_PULLDOWN) },
 
-#include "genhdr/pins-af-const.h"
+#include "genhdr/pins_af_const.h"
 };
 
 STATIC MP_DEFINE_CONST_DICT(pin_locals_dict, pin_locals_dict_table);
diff --git a/teensy/Makefile b/teensy/Makefile
index 5b8e26621..c627f2fa6 100644
--- a/teensy/Makefile
+++ b/teensy/Makefile
@@ -133,13 +133,13 @@ $(BUILD)/%.hex: $(BUILD)/%.elf
 	$(Q)$(OBJCOPY) -O ihex -R .eeprom "$<" "$@"
 
 MAKE_PINS = make-pins.py
-BOARD_PINS = teensy-pins.csv
-AF_FILE = mk20dx256-af.csv
-PREFIX_FILE = mk20dx256-prefix.c
+BOARD_PINS = teensy_pins.csv
+AF_FILE = mk20dx256_af.csv
+PREFIX_FILE = mk20dx256_prefix.c
 GEN_PINS_SRC = $(BUILD)/pins_gen.c
 GEN_PINS_HDR = $(HEADER_BUILD)/pins.h
 GEN_PINS_QSTR = $(BUILD)/pins_qstr.h
-GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins-af-const.h
+GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins_af_const.h
 
 # Making OBJ use an order-only depenedency on the generated pins.h file
 # has the side effect of making the pins.h file before we actually compile
@@ -150,7 +150,7 @@ $(OBJ): | $(HEADER_BUILD)/pins.h
 
 # Use a pattern rule here so that make will only call make-pins.py once to make
 # both pins_$(BOARD).c and pins.h
-$(BUILD)/%_gen.c $(HEADER_BUILD)/%.h $(HEADER_BUILD)/%-af-const.h $(BUILD)/%_qstr.h: teensy-%.csv $(MAKE_PINS) $(AF_FILE) $(PREFIX_FILE) | $(HEADER_BUILD)
+$(BUILD)/%_gen.c $(HEADER_BUILD)/%.h $(HEADER_BUILD)/%_af_const.h $(BUILD)/%_qstr.h: teensy_%.csv $(MAKE_PINS) $(AF_FILE) $(PREFIX_FILE) | $(HEADER_BUILD)
 	$(ECHO) "Create $@"
 	$(Q)$(PYTHON) $(MAKE_PINS) --board $(BOARD_PINS) --af $(AF_FILE) --prefix $(PREFIX_FILE) --hdr $(GEN_PINS_HDR) --qstr $(GEN_PINS_QSTR) --af-const $(GEN_PINS_AF_CONST) > $(GEN_PINS_SRC)
 
diff --git a/teensy/mk20dx256-af.csv b/teensy/mk20dx256_af.csv
similarity index 100%
rename from teensy/mk20dx256-af.csv
rename to teensy/mk20dx256_af.csv
diff --git a/teensy/mk20dx256-prefix.c b/teensy/mk20dx256_prefix.c
similarity index 100%
rename from teensy/mk20dx256-prefix.c
rename to teensy/mk20dx256_prefix.c
diff --git a/teensy/teensy-pins.csv b/teensy/teensy_pins.csv
similarity index 100%
rename from teensy/teensy-pins.csv
rename to teensy/teensy_pins.csv