diff --git a/firmware/ice40-riscv/common/spi.c b/firmware/ice40-riscv/common/spi.c
index 6683a5a..94cabb0 100644
--- a/firmware/ice40-riscv/common/spi.c
+++ b/firmware/ice40-riscv/common/spi.c
@@ -95,7 +95,7 @@
 
 	/* Run the chunks */
 	while (n--) {
-		for (int i=0; i<xfer->len; i++)
+		for (unsigned int i=0; i<xfer->len; i++)
 		{
 			spi_regs[chan]->txdr = xfer->write ? xfer->data[i] : 0x00;
 			while (!(spi_regs[chan]->sr & SPI_SR_RRDY));
diff --git a/firmware/ice40-riscv/e1-tracer/e1.c b/firmware/ice40-riscv/e1-tracer/e1.c
index 989d2c8..dc2ae11 100644
--- a/firmware/ice40-riscv/e1-tracer/e1.c
+++ b/firmware/ice40-riscv/e1-tracer/e1.c
@@ -176,7 +176,7 @@
 }
 
 static unsigned int
-e1f_frame_read(struct e1_fifo *fifo, unsigned int *ofs, int max_frames)
+e1f_frame_read(struct e1_fifo *fifo, unsigned int *ofs, unsigned int max_frames)
 {
 	unsigned int lu, le;
 
diff --git a/firmware/ice40-riscv/icE1usb/e1.c b/firmware/ice40-riscv/icE1usb/e1.c
index 0e14b6f..17be75d 100644
--- a/firmware/ice40-riscv/icE1usb/e1.c
+++ b/firmware/ice40-riscv/icE1usb/e1.c
@@ -191,7 +191,7 @@
 }
 
 static unsigned int
-e1f_frame_read(struct e1_fifo *fifo, unsigned int *ofs, int max_frames)
+e1f_frame_read(struct e1_fifo *fifo, unsigned int *ofs, unsigned int max_frames)
 {
 	unsigned int lu, le;