diff --git a/src/class/audio/audio_device.c b/src/class/audio/audio_device.c
index 8dd1a8fe..61676022 100644
--- a/src/class/audio/audio_device.c
+++ b/src/class/audio/audio_device.c
@@ -537,7 +537,7 @@ static bool audiod_tx_done_cb(uint8_t rhport, audiod_interface_t* audio, uint16_
   // TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_in, audio->epin_buf, audio->epin_buf_cnt));
 
 
-  TU_VERIFY(usbd_edpt_ISO_xfer(rhport, audio->ep_in, &audio->epin_ff));
+  TU_VERIFY(usbd_edpt_iso_xfer(rhport, audio->ep_in, &audio->epin_ff));
 
 
 
diff --git a/src/device/dcd.h b/src/device/dcd.h
index 1b2d2b94..30224e16 100644
--- a/src/device/dcd.h
+++ b/src/device/dcd.h
@@ -135,7 +135,7 @@ void dcd_edpt_close        (uint8_t rhport, uint8_t ep_addr) TU_ATTR_WEAK;
 bool dcd_edpt_xfer        (uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes);
 
 // Submit an ISO transfer, When complete dcd_event_xfer_complete() is invoked to notify the stack
-bool dcd_edpt_ISO_xfer    (uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff);
+bool dcd_edpt_iso_xfer    (uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff);
 
 // Stall endpoint
 void dcd_edpt_stall       (uint8_t rhport, uint8_t ep_addr);
diff --git a/src/device/usbd.c b/src/device/usbd.c
index e0546ac3..c2b5b65d 100644
--- a/src/device/usbd.c
+++ b/src/device/usbd.c
@@ -1206,7 +1206,7 @@ bool usbd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t
   }
 }
 
-bool usbd_edpt_ISO_xfer(uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff)
+bool usbd_edpt_iso_xfer(uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff)
 {
   uint8_t const epnum = tu_edpt_number(ep_addr);
   uint8_t const dir   = tu_edpt_dir(ep_addr);
@@ -1220,7 +1220,7 @@ bool usbd_edpt_ISO_xfer(uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff)
   // and usbd task can preempt and clear the busy
   _usbd_dev.ep_status[epnum][dir].busy = true;
 
-  if ( dcd_edpt_ISO_xfer(rhport, ep_addr, ff) )
+  if ( dcd_edpt_iso_xfer(rhport, ep_addr, ff) )
   {
     TU_LOG2("OK\r\n");
     return true;
diff --git a/src/device/usbd_pvt.h b/src/device/usbd_pvt.h
index 4ae55aec..1d24957a 100644
--- a/src/device/usbd_pvt.h
+++ b/src/device/usbd_pvt.h
@@ -73,7 +73,7 @@ void usbd_edpt_close(uint8_t rhport, uint8_t ep_addr);
 bool usbd_edpt_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes);
 
 // Submit a usb ISO transfer by use of a FIFO (ring buffer) - all bytes in FIFO get transmitted
-bool usbd_edpt_ISO_xfer(uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff);
+bool usbd_edpt_iso_xfer(uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff);
 
 // Claim an endpoint before submitting a transfer.
 // If caller does not make any transfer, it must release endpoint for others.
diff --git a/src/portable/st/synopsys/dcd_synopsys.c b/src/portable/st/synopsys/dcd_synopsys.c
index 5f9dc267..90fcd51e 100644
--- a/src/portable/st/synopsys/dcd_synopsys.c
+++ b/src/portable/st/synopsys/dcd_synopsys.c
@@ -670,7 +670,7 @@ bool dcd_edpt_xfer (uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t
   return true;
 }
 
-bool dcd_edpt_ISO_xfer (uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff)
+bool dcd_edpt_iso_xfer (uint8_t rhport, uint8_t ep_addr, tu_fifo_t * ff)
 {
   // USB buffers always work in bytes so to avoid unnecessary divisions we demand item_size = 1
   TU_ASSERT(ff->item_size == 1);