diff --git a/firmware/console/binary/serial_can.cpp b/firmware/console/binary/serial_can.cpp
index c7364f5c61..3f2360d927 100644
--- a/firmware/console/binary/serial_can.cpp
+++ b/firmware/console/binary/serial_can.cpp
@@ -141,8 +141,8 @@ int CanStreamerState::receiveFrame(CANRxFrame *rxmsg, uint8_t *buf, int num, can
 		memcpy(buf, srcBuf, numBytesToCopy);
 	}
 	srcBuf += numBytesToCopy;
+	waitingForNumBytes -= numBytesAvailable;
 	numBytesAvailable -= numBytesToCopy;
-	waitingForNumBytes -= numBytesToCopy;
 	// if there are some more bytes left, we save them for the next time
 	for (int i = 0; i < numBytesAvailable; i++) {
 		rxFifoBuf.put(srcBuf[i]);
diff --git a/unit_tests/tests/test_can_serial.cpp b/unit_tests/tests/test_can_serial.cpp
index 52431df204..6a591be2b7 100644
--- a/unit_tests/tests/test_can_serial.cpp
+++ b/unit_tests/tests/test_can_serial.cpp
@@ -110,13 +110,15 @@ public:
 		for (size_t i = 0; i < totalSize; i++) {
 			EXPECT_EQ(totalData[i], totalReceivedData[i]) << "Rcv. byte #" << i << " differs!";
 		}
+		// check the FIFO buf size
+		EXPECT_EQ(0, rxFifoBuf.getCount());
+
 	}
 
 protected:
 	TestCanStreamer streamer;
 };
 
-
 TEST(testCanSerial, test1Frame) {
 
 	{
@@ -146,6 +148,10 @@ TEST(testCanSerial, test2Frames) {
 		TestCanStreamerState state;
 		state.test({ "01234567" }, { "\x10"s "\x08"s "012345"s, "\x21"s "67\0\0\0\0\0"s }, 8, { 8 }); // 8 bytes -> 2 8-byte frames, 8 bytes in FIFO
 	}
+	{
+		TestCanStreamerState state;
+		state.test({ "0123456789A" }, { "\x10"s "\x0B"s "012345"s, "\x21"s "6789A\0\0"s }, 11, { 2, 5, 4 }); // 11 bytes -> 2 8-byte frames
+	}
 	/*
 	{
 		TestCanStreamerState state;