diff --git a/firmware/ice40-riscv/icE1usb/e1.c b/firmware/ice40-riscv/icE1usb/e1.c
index f5e367e..59be063 100644
--- a/firmware/ice40-riscv/icE1usb/e1.c
+++ b/firmware/ice40-riscv/icE1usb/e1.c
@@ -21,13 +21,13 @@
 static volatile struct e1_core * const e1_regs = (void *)(E1_CORE_BASE);
 static volatile uint8_t * const e1_data = (void *)(E1_DATA_BASE);
 
-unsigned int
+static unsigned int
 e1_data_ofs(int mf, int frame, int ts)
 {
 	return (mf << 9) | (frame << 5) | ts;
 }
 
-volatile uint8_t *
+static volatile uint8_t *
 e1_data_ptr(int mf, int frame, int ts)
 {
 	return &e1_data[e1_data_ofs(mf, frame, ts)];
diff --git a/firmware/ice40-riscv/icE1usb/e1.h b/firmware/ice40-riscv/icE1usb/e1.h
index 4394638..4cbb6e5 100644
--- a/firmware/ice40-riscv/icE1usb/e1.h
+++ b/firmware/ice40-riscv/icE1usb/e1.h
@@ -28,9 +28,6 @@
 
 const struct e1_error_count *e1_get_error_count(void);
 
-volatile uint8_t *e1_data_ptr(int mf, int frame, int ts);
-unsigned int e1_data_ofs(int mf, int frame, int ts);
-
 enum e1_platform_led {
 	E1P_LED_GREEN		= 0,
 	E1P_LED_YELLOW		= 1,