diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 385acb89..3f94ac3 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -268,7 +268,7 @@
 				dev_err(dev, "usb_bulk_msg returned %d\n", rv);
 				goto exit;
 			}
-		} while ((actual = max_size) &&
+		} while ((actual == max_size) &&
 			 (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
 
 	if (actual == max_size) {