diff --git a/include/ecrt.h b/include/ecrt.h
index 754821f6..ba36d4d3 100644
--- a/include/ecrt.h
+++ b/include/ecrt.h
@@ -2472,8 +2472,9 @@ ec_request_state_t ecrt_reg_request_state(
  * activation).
  *
  * \ingroup ApplicationInterfaceRT
+ * \return 0 on success, otherwise negative error code.
  */
-EC_PUBLIC_API void ecrt_reg_request_write(
+EC_PUBLIC_API int ecrt_reg_request_write(
         ec_reg_request_t *req, /**< Register request. */
         uint16_t address, /**< Register address. */
         size_t size /**< Size to write. */
@@ -2491,8 +2492,9 @@ EC_PUBLIC_API void ecrt_reg_request_write(
  * activation).
  *
  * \ingroup ApplicationInterfaceRT
+ * \return 0 on success, otherwise negative error code.
  */
-EC_PUBLIC_API void ecrt_reg_request_read(
+EC_PUBLIC_API int ecrt_reg_request_read(
         ec_reg_request_t *req, /**< Register request. */
         uint16_t address, /**< Register address. */
         size_t size /**< Size to write. */
diff --git a/lib/reg_request.c b/lib/reg_request.c
index 6fb04c98..f52afd15 100644
--- a/lib/reg_request.c
+++ b/lib/reg_request.c
@@ -89,7 +89,7 @@ ec_request_state_t ecrt_reg_request_state(const ec_reg_request_t *reg)
 
 /****************************************************************************/
 
-void ecrt_reg_request_write(ec_reg_request_t *reg, uint16_t address,
+int ecrt_reg_request_write(ec_reg_request_t *reg, uint16_t address,
         size_t size)
 {
     ec_ioctl_reg_request_t io;
@@ -103,14 +103,14 @@ void ecrt_reg_request_write(ec_reg_request_t *reg, uint16_t address,
 
     ret = ioctl(reg->config->master->fd, EC_IOCTL_REG_REQUEST_WRITE, &io);
     if (EC_IOCTL_IS_ERROR(ret)) {
-        fprintf(stderr, "Failed to command an register write operation: %s\n",
-                strerror(EC_IOCTL_ERRNO(ret)));
+        return -EC_IOCTL_ERRNO(ret);
     }
+    return 0;
 }
 
 /****************************************************************************/
 
-void ecrt_reg_request_read(ec_reg_request_t *reg, uint16_t address,
+int ecrt_reg_request_read(ec_reg_request_t *reg, uint16_t address,
         size_t size)
 {
     ec_ioctl_reg_request_t io;
@@ -123,9 +123,9 @@ void ecrt_reg_request_read(ec_reg_request_t *reg, uint16_t address,
 
     ret = ioctl(reg->config->master->fd, EC_IOCTL_REG_REQUEST_READ, &io);
     if (EC_IOCTL_IS_ERROR(ret)) {
-        fprintf(stderr, "Failed to command an register read operation: %s\n",
-                strerror(EC_IOCTL_ERRNO(ret)));
+        return -EC_IOCTL_ERRNO(ret);
     }
+    return 0;
 }
 
 /****************************************************************************/
diff --git a/master/ioctl.c b/master/ioctl.c
index ed07d063..1289e27d 100644
--- a/master/ioctl.c
+++ b/master/ioctl.c
@@ -1069,7 +1069,10 @@ static ATTRIBUTES int ec_ioctl_slave_reg_read(
         return ret;
     }
 
-    ecrt_reg_request_read(&request, io.address, io.size);
+    ret = ecrt_reg_request_read(&request, io.address, io.size);
+    if (ret) {
+        return ret;
+    }
 
     if (down_interruptible(&master->master_sem)) {
         ec_reg_request_clear(&request);
@@ -1153,7 +1156,10 @@ static ATTRIBUTES int ec_ioctl_slave_reg_write(
         return -EFAULT;
     }
 
-    ecrt_reg_request_write(&request, io.address, io.size);
+    ret = ecrt_reg_request_write(&request, io.address, io.size);
+    if (ret) {
+        return ret;
+    }
 
     if (down_interruptible(&master->master_sem)) {
         ec_reg_request_clear(&request);
@@ -4050,8 +4056,7 @@ static ATTRIBUTES int ec_ioctl_reg_request_write(
         return -EFAULT;
     }
 
-    ecrt_reg_request_write(reg, io.address, io.transfer_size);
-    return 0;
+    return ecrt_reg_request_write(reg, io.address, io.transfer_size);
 }
 
 /****************************************************************************/
@@ -4093,8 +4098,7 @@ static ATTRIBUTES int ec_ioctl_reg_request_read(
         return -EOVERFLOW;
     }
 
-    ecrt_reg_request_read(reg, io.address, io.transfer_size);
-    return 0;
+    return ecrt_reg_request_read(reg, io.address, io.transfer_size);
 }
 
 /****************************************************************************/
diff --git a/master/reg_request.c b/master/reg_request.c
index 29f7d4e2..eab70b1d 100644
--- a/master/reg_request.c
+++ b/master/reg_request.c
@@ -89,24 +89,26 @@ ec_request_state_t ecrt_reg_request_state(const ec_reg_request_t *reg)
 
 /****************************************************************************/
 
-void ecrt_reg_request_write(ec_reg_request_t *reg, uint16_t address,
+int ecrt_reg_request_write(ec_reg_request_t *reg, uint16_t address,
         size_t size)
 {
     reg->dir = EC_DIR_OUTPUT;
     reg->address = address;
     reg->transfer_size = min(size, reg->mem_size);
     reg->state = EC_INT_REQUEST_QUEUED;
+    return 0;
 }
 
 /****************************************************************************/
 
-void ecrt_reg_request_read(ec_reg_request_t *reg, uint16_t address,
+int ecrt_reg_request_read(ec_reg_request_t *reg, uint16_t address,
         size_t size)
 {
     reg->dir = EC_DIR_INPUT;
     reg->address = address;
     reg->transfer_size = min(size, reg->mem_size);
     reg->state = EC_INT_REQUEST_QUEUED;
+    return 0;
 }
 
 /****************************************************************************/