diff --git a/firmware/config/boards/hellen/alphax-4chan/board.mk b/firmware/config/boards/hellen/alphax-4chan/board.mk
index 8eb4c98f40..5a11d90ad4 100644
--- a/firmware/config/boards/hellen/alphax-4chan/board.mk
+++ b/firmware/config/boards/hellen/alphax-4chan/board.mk
@@ -18,7 +18,10 @@ DDEFS += -DDISABLE_PIN_STATE_VALIDATION=TRUE
 
 include $(BOARDS_DIR)/hellen/hellen-common144.mk
 
-DDEFS += $(PRIMARY_COMMUNICATION_PORT_USART2)
+# serial ports only on F4
+ifeq ($(PROJECT_CPU),ARCH_STM32F4)
+	DDEFS += $(PRIMARY_COMMUNICATION_PORT_USART2)
+endif
 
 ifeq ($(PROJECT_CPU),ARCH_STM32F7)
 	DDEFS += -DSHORT_BOARD_NAME=alphax-4chan-f7
diff --git a/firmware/config/boards/hellen/alphax-4chan/compile_alphax-4chan_7.sh b/firmware/config/boards/hellen/alphax-4chan/compile_alphax-4chan_f7.sh
old mode 100644
new mode 100755
similarity index 100%
rename from firmware/config/boards/hellen/alphax-4chan/compile_alphax-4chan_7.sh
rename to firmware/config/boards/hellen/alphax-4chan/compile_alphax-4chan_f7.sh
diff --git a/firmware/config/boards/hellen/alphax-8chan/board.mk b/firmware/config/boards/hellen/alphax-8chan/board.mk
index 856059cb2a..4dbabf4bca 100644
--- a/firmware/config/boards/hellen/alphax-8chan/board.mk
+++ b/firmware/config/boards/hellen/alphax-8chan/board.mk
@@ -15,6 +15,9 @@ DDEFS += -DADC_MUX_PIN=Gpio::B3
 
 include $(BOARDS_DIR)/hellen/hellen-common144.mk
 
-DDEFS += $(PRIMARY_COMMUNICATION_PORT_USART2)
+# serial ports only on F4
+ifeq ($(PROJECT_CPU),ARCH_STM32F4)
+	DDEFS += $(PRIMARY_COMMUNICATION_PORT_USART2)
+endif
 
 DDEFS += -DSHORT_BOARD_NAME=alphax-8chan
diff --git a/firmware/config/boards/hellen/alphax-8chan/compile_alphax-8chan.sh b/firmware/config/boards/hellen/alphax-8chan/compile_alphax-8chan.sh
old mode 100644
new mode 100755
diff --git a/firmware/config/boards/hellen/alphax-8chan/compile_alphax-8chan_f7.sh b/firmware/config/boards/hellen/alphax-8chan/compile_alphax-8chan_f7.sh
old mode 100644
new mode 100755