diff --git a/lib_xua/src/core/buffer/ep/ep_buffer.xc b/lib_xua/src/core/buffer/ep/ep_buffer.xc
index 2093502f..9a995f8d 100644
--- a/lib_xua/src/core/buffer/ep/ep_buffer.xc
+++ b/lib_xua/src/core/buffer/ep/ep_buffer.xc
@@ -36,9 +36,10 @@ extern unsigned int g_curSamFreqMultiplier;
 #define SET_SHARED_GLOBAL0(x,y) SET_SHARED_GLOBAL(x,y)
 #endif
 
-
-/* Global var for speed.  Related to feedback. Used by input stream to determine IN packet size */
-unsigned g_speed;
+/* Initialise g_speed now so we get a sensible packet size until we start properly calculating feedback in the SoF case */
+/* Without this, zero size input packets fill the input FIFO and it takes a long time to clear out when feedback starts */
+/* This can cause a delay to the decouple ISR being serviced pushing our I2S timing. Initialising solves this */
+unsigned g_speed = (AUDIO_CLASS == 2) ? (DEFAULT_FREQ/8000) << 16 : (DEFAULT_FREQ/1000) << 16;
 unsigned g_freqChange = 0;
 unsigned feedbackValid = 0;