diff --git a/tests/test_i2s_loopback.py b/tests/test_i2s_loopback.py
index 471c729d..fdf67bae 100644
--- a/tests/test_i2s_loopback.py
+++ b/tests/test_i2s_loopback.py
@@ -71,7 +71,7 @@ def do_test(
 @pytest.mark.parametrize("i2s_role", ["master", "slave"])
 @pytest.mark.parametrize("pcm_format", ["i2s", "tdm"])
 @pytest.mark.parametrize("channel_count", [2, 8, 16])
-@pytest.mark.parametrize("word_length", [32]) # I2S world length in bits
+@pytest.mark.parametrize("word_length", [16, 32]) # I2S world length in bits
 @pytest.mark.parametrize("sample_rate", [48000, 96000, 192000])
 def test_i2s_loopback(
     i2s_role, pcm_format, channel_count, sample_rate, word_length, test_file, options, capfd
diff --git a/tests/test_i2s_loopback/main.xc b/tests/test_i2s_loopback/main.xc
index a98bc9ec..b0043f27 100644
--- a/tests/test_i2s_loopback/main.xc
+++ b/tests/test_i2s_loopback/main.xc
@@ -1,4 +1,4 @@
-// Copyright 2016-2022 XMOS LIMITED.
+// Copyright 2016-2023 XMOS LIMITED.
 // This Software is subject to the terms of the XMOS Public Licence: Version 1.
 #include <platform.h>
 #include <stdlib.h>
@@ -92,9 +92,10 @@ clock clk_audio_mclk                = on tile[AUDIO_IO_TILE]: XS1_CLKBLK_2;   /*
 #define TOTAL_TEST_FRAMES (5 * DEFAULT_FREQ)
 #endif
 
-#define SAMPLE(frame_count, channel_num) (((frame_count) << 8) | ((channel_num) & 0xFF))
-#define SAMPLE_FRAME_NUM(test_word) ((test_word) >> 8)
-#define SAMPLE_CHANNEL_NUM(test_word) ((test_word) & 0xFF)
+#define SHIFT (16) /* Note, we shift samples up such that we can test down to 16bit I2S */
+#define SAMPLE(frame_count, channel_num) ((((frame_count) << 8) | ((channel_num) & 0xFF))<<SHIFT)
+#define SAMPLE_FRAME_NUM(test_word) ((test_word>>SHIFT) >> 8)
+#define SAMPLE_CHANNEL_NUM(test_word) ((test_word>>SHIFT) & 0xFF)
 
 void generator(chanend c_checker, chanend c_out)
 {
@@ -105,7 +106,6 @@ void generator(chanend c_checker, chanend c_out)
 
   frame_count = 0;
 
-
   while (1) {
     underflow_word = inuint(c_out);