diff --git a/arch/arm/src/stm32/stm32_otgfsdev.c b/arch/arm/src/stm32/stm32_otgfsdev.c
index 64ff4ac066..b8341666c2 100644
--- a/arch/arm/src/stm32/stm32_otgfsdev.c
+++ b/arch/arm/src/stm32/stm32_otgfsdev.c
@@ -653,7 +653,7 @@ static void        stm32_ep_freereq(FAR struct usbdev_ep_s *ep,
 /* Endpoint buffer management */
 
 #ifdef CONFIG_USBDEV_DMA
-static void       *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes);
+static void       *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uin16_t bytes);
 static void        stm32_ep_freebuffer(FAR struct usbdev_ep_s *ep, FAR void *buf);
 #endif
 
@@ -4335,7 +4335,7 @@ static void stm32_ep_freereq(FAR struct usbdev_ep_s *ep, FAR struct usbdev_req_s
  ****************************************************************************/
 
 #ifdef CONFIG_USBDEV_DMA
-static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes)
+static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uint16_t bytes)
 {
   usbtrace(TRACE_EPALLOCBUFFER, ((FAR struct stm32_ep_s *)ep)->epphy);
 
diff --git a/arch/arm/src/stm32/stm32_otghsdev.c b/arch/arm/src/stm32/stm32_otghsdev.c
index 833839f0f6..f5108a5f7e 100644
--- a/arch/arm/src/stm32/stm32_otghsdev.c
+++ b/arch/arm/src/stm32/stm32_otghsdev.c
@@ -605,7 +605,7 @@ static void        stm32_ep_freereq(FAR struct usbdev_ep_s *ep,
 /* Endpoint buffer management */
 
 #ifdef CONFIG_USBDEV_DMA
-static void       *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes);
+static void       *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uint16_t bytes);
 static void        stm32_ep_freebuffer(FAR struct usbdev_ep_s *ep, FAR void *buf);
 #endif
 
@@ -4284,7 +4284,7 @@ static void stm32_ep_freereq(FAR struct usbdev_ep_s *ep, FAR struct usbdev_req_s
  ****************************************************************************/
 
 #ifdef CONFIG_USBDEV_DMA
-static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes)
+static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uint16_t bytes)
 {
   usbtrace(TRACE_EPALLOCBUFFER, privep->epphy);
 
diff --git a/arch/arm/src/stm32f7/stm32_otgdev.c b/arch/arm/src/stm32f7/stm32_otgdev.c
index e71198f1a7..710ffa774f 100644
--- a/arch/arm/src/stm32f7/stm32_otgdev.c
+++ b/arch/arm/src/stm32f7/stm32_otgdev.c
@@ -684,7 +684,7 @@ static void        stm32_ep_freereq(FAR struct usbdev_ep_s *ep,
 
 #ifdef CONFIG_USBDEV_DMA
 static void       *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep,
-                     unsigned bytes);
+                     uint16_t bytes);
 static void        stm32_ep_freebuffer(FAR struct usbdev_ep_s *ep,
                      FAR void *buf);
 #endif
@@ -4356,7 +4356,7 @@ static void stm32_ep_freereq(FAR struct usbdev_ep_s *ep, FAR struct usbdev_req_s
  ****************************************************************************/
 
 #ifdef CONFIG_USBDEV_DMA
-static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes)
+static void *stm32_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uint16_t bytes)
 {
   usbtrace(TRACE_EPALLOCBUFFER, ((FAR struct stm32_ep_s *)ep)->epphy);
 
diff --git a/arch/arm/src/stm32l4/stm32l4_otgfsdev.c b/arch/arm/src/stm32l4/stm32l4_otgfsdev.c
index f59954d53e..97e7fa9549 100644
--- a/arch/arm/src/stm32l4/stm32l4_otgfsdev.c
+++ b/arch/arm/src/stm32l4/stm32l4_otgfsdev.c
@@ -712,7 +712,7 @@ static void        stm32l4_ep_freereq(FAR struct usbdev_ep_s *ep,
 
 #ifdef CONFIG_USBDEV_DMA
 static void       *stm32l4_ep_allocbuffer(FAR struct usbdev_ep_s *ep,
-                     unsigned bytes);
+                     uint16_t bytes);
 static void        stm32l4_ep_freebuffer(FAR struct usbdev_ep_s *ep,
                      FAR void *buf);
 #endif
@@ -4406,7 +4406,7 @@ static void stm32l4_ep_freereq(FAR struct usbdev_ep_s *ep, FAR struct usbdev_req
  ****************************************************************************/
 
 #ifdef CONFIG_USBDEV_DMA
-static void *stm32l4_ep_allocbuffer(FAR struct usbdev_ep_s *ep, unsigned bytes)
+static void *stm32l4_ep_allocbuffer(FAR struct usbdev_ep_s *ep, uint16_t bytes)
 {
   usbtrace(TRACE_EPALLOCBUFFER, ((FAR struct stm32l4_ep_s *)ep)->epphy);