diff --git a/firmware/hackrf_usb/usb.c b/firmware/hackrf_usb/usb.c
index 14a94397..09e3d127 100644
--- a/firmware/hackrf_usb/usb.c
+++ b/firmware/hackrf_usb/usb.c
@@ -188,6 +188,17 @@ void usb_endpoint_prime(
 	}
 }
 
+static bool usb_endpoint_is_priming(
+	const usb_endpoint_t* const endpoint
+) {
+	const uint_fast8_t endpoint_number = usb_endpoint_number(endpoint->address);
+	if( usb_endpoint_is_in(endpoint->address) ) {
+		return USB0_ENDPTPRIME & USB0_ENDPTPRIME_PETB(1 << endpoint_number);
+	} else {
+		return USB0_ENDPTPRIME & USB0_ENDPTPRIME_PERB(1 << endpoint_number);
+	}
+}
+
 // Schedule an already filled-in transfer descriptor for execution on
 // the given endpoint, waiting until the endpoint has finished.
 void usb_endpoint_schedule_wait(
@@ -213,18 +224,13 @@ void usb_endpoint_schedule_append(
         usb_transfer_descriptor_t* const tail_td,
         usb_transfer_descriptor_t* const new_td
 ) {
-        const uint_fast8_t endpoint_number = usb_endpoint_number(endpoint->address);
         bool done;
 
         tail_td->next_dtd_pointer = new_td;
 
         do {
-                if( usb_endpoint_is_in(endpoint->address) ) {
-                        if (USB0_ENDPTPRIME & USB0_ENDPTPRIME_PETB(1 << endpoint_number) )
-                                return;
-                } else {
-                        if (USB0_ENDPTPRIME & USB0_ENDPTPRIME_PERB(1 << endpoint_number) )
-                                return;
+                if (usb_endpoint_is_priming(endpoint)) {
+                        return;
                 }
 
                 USB0_USBCMD_D |= USB0_USBCMD_D_ATDTW;
@@ -237,18 +243,6 @@ void usb_endpoint_schedule_append(
         }
 }
 
-/*
-static bool usb_endpoint_is_priming(
-	const usb_endpoint_t* const endpoint
-) {
-	const uint_fast8_t endpoint_number = usb_endpoint_number(endpoint->address);
-	if( usb_endpoint_is_in(endpoint->address) ) {
-		return USB0_ENDPTPRIME & USB0_ENDPTPRIME_PETB(1 << endpoint_number);
-	} else {
-		return USB0_ENDPTPRIME & USB0_ENDPTPRIME_PERB(1 << endpoint_number);
-	}
-}
-*/
 void usb_endpoint_flush(
 	const usb_endpoint_t* const endpoint
 ) {