diff --git a/module_usb_audio/devicedefines.h b/module_usb_audio/devicedefines.h
index f4248cf5..66e0dd63 100644
--- a/module_usb_audio/devicedefines.h
+++ b/module_usb_audio/devicedefines.h
@@ -488,8 +488,12 @@
 #define MIX_INPUTS                  18
 #endif
 
-#ifndef MAX_MIX_COUNT
-#define MAX_MIX_COUNT               8
+#ifdef MIXER
+    #ifndef MAX_MIX_COUNT
+    #define MAX_MIX_COUNT        8
+    #endif
+#else
+    #define MAX_MIX_COUNT        0
 #endif
 
 
diff --git a/module_usb_audio/endpoint0/descriptors.h b/module_usb_audio/endpoint0/descriptors.h
index a12937b9..76518a44 100644
--- a/module_usb_audio/endpoint0/descriptors.h
+++ b/module_usb_audio/endpoint0/descriptors.h
@@ -268,7 +268,11 @@ enum {
 #endif
 #endif
 #ifdef IAP
+    #ifdef MIXER
     IAP_INTERFACE_STRING_INDEX = INPUT_INTERFACE_LAST_STRING_INDEX + MAX_MIX_COUNT + 1,
+    #else
+    IAP_INTERFACE_STRING_INDEX = INPUT_INTERFACE_LAST_STRING_INDEX,
+    #endif
 #endif
 };