diff --git a/drivers/virt/vboxguest/vboxguest_core.c b/drivers/virt/vboxguest/vboxguest_core.c
index 2307b0329aec..4eb8ea36093a 100644
--- a/drivers/virt/vboxguest/vboxguest_core.c
+++ b/drivers/virt/vboxguest/vboxguest_core.c
@@ -1519,7 +1519,8 @@ int vbg_core_ioctl(struct vbg_session *session, unsigned int req, void *data)
 
 	/* For VMMDEV_REQUEST hdr->type != VBG_IOCTL_HDR_TYPE_DEFAULT */
 	if (req_no_size == VBG_IOCTL_VMMDEV_REQUEST(0) ||
-	    req == VBG_IOCTL_VMMDEV_REQUEST_BIG)
+	    req == VBG_IOCTL_VMMDEV_REQUEST_BIG ||
+	    req == VBG_IOCTL_VMMDEV_REQUEST_BIG_ALT)
 		return vbg_ioctl_vmmrequest(gdev, session, data);
 
 	if (hdr->type != VBG_IOCTL_HDR_TYPE_DEFAULT)
@@ -1557,6 +1558,7 @@ int vbg_core_ioctl(struct vbg_session *session, unsigned int req, void *data)
 	case VBG_IOCTL_HGCM_CALL(0):
 		return vbg_ioctl_hgcm_call(gdev, session, f32bit, data);
 	case VBG_IOCTL_LOG(0):
+	case VBG_IOCTL_LOG_ALT(0):
 		return vbg_ioctl_log(data);
 	}
 
diff --git a/drivers/virt/vboxguest/vboxguest_core.h b/drivers/virt/vboxguest/vboxguest_core.h
index 4188c12b839f..77c3a9c8255d 100644
--- a/drivers/virt/vboxguest/vboxguest_core.h
+++ b/drivers/virt/vboxguest/vboxguest_core.h
@@ -15,6 +15,21 @@
 #include <linux/vboxguest.h>
 #include "vmmdev.h"
 
+/*
+ * The mainline kernel version (this version) of the vboxguest module
+ * contained a bug where it defined VBGL_IOCTL_VMMDEV_REQUEST_BIG and
+ * VBGL_IOCTL_LOG using _IOC(_IOC_READ | _IOC_WRITE, 'V', ...) instead
+ * of _IO(V, ...) as the out of tree VirtualBox upstream version does.
+ *
+ * These _ALT definitions keep compatibility with the wrong defines the
+ * mainline kernel version used for a while.
+ * Note the VirtualBox userspace bits have always been built against
+ * VirtualBox upstream's headers, so this is likely not necessary. But
+ * we must never break our ABI so we keep these around to be 100% sure.
+ */
+#define VBG_IOCTL_VMMDEV_REQUEST_BIG_ALT _IOC(_IOC_READ | _IOC_WRITE, 'V', 3, 0)
+#define VBG_IOCTL_LOG_ALT(s)             _IOC(_IOC_READ | _IOC_WRITE, 'V', 9, s)
+
 struct vbg_session;
 
 /** VBox guest memory balloon. */
diff --git a/drivers/virt/vboxguest/vboxguest_linux.c b/drivers/virt/vboxguest/vboxguest_linux.c
index 6e8c0f1c1056..32c2c52f7e84 100644
--- a/drivers/virt/vboxguest/vboxguest_linux.c
+++ b/drivers/virt/vboxguest/vboxguest_linux.c
@@ -131,7 +131,8 @@ static long vbg_misc_device_ioctl(struct file *filp, unsigned int req,
 	 * the need for a bounce-buffer and another copy later on.
 	 */
 	is_vmmdev_req = (req & ~IOCSIZE_MASK) == VBG_IOCTL_VMMDEV_REQUEST(0) ||
-			 req == VBG_IOCTL_VMMDEV_REQUEST_BIG;
+			 req == VBG_IOCTL_VMMDEV_REQUEST_BIG ||
+			 req == VBG_IOCTL_VMMDEV_REQUEST_BIG_ALT;
 
 	if (is_vmmdev_req)
 		buf = vbg_req_alloc(size, VBG_IOCTL_HDR_TYPE_DEFAULT,
diff --git a/include/uapi/linux/vboxguest.h b/include/uapi/linux/vboxguest.h
index 9cec58a6a5ea..f79d7abe27db 100644
--- a/include/uapi/linux/vboxguest.h
+++ b/include/uapi/linux/vboxguest.h
@@ -103,7 +103,7 @@ VMMDEV_ASSERT_SIZE(vbg_ioctl_driver_version_info, 24 + 20);
 
 
 /* IOCTL to perform a VMM Device request larger then 1KB. */
-#define VBG_IOCTL_VMMDEV_REQUEST_BIG	_IOC(_IOC_READ | _IOC_WRITE, 'V', 3, 0)
+#define VBG_IOCTL_VMMDEV_REQUEST_BIG	_IO('V', 3)
 
 
 /** VBG_IOCTL_HGCM_CONNECT data structure. */
@@ -198,7 +198,7 @@ struct vbg_ioctl_log {
 	} u;
 };
 
-#define VBG_IOCTL_LOG(s)		_IOC(_IOC_READ | _IOC_WRITE, 'V', 9, s)
+#define VBG_IOCTL_LOG(s)		_IO('V', 9)
 
 
 /** VBG_IOCTL_WAIT_FOR_EVENTS data structure. */