diff --git a/module_usb_audio/endpoint0/descriptors.h b/module_usb_audio/endpoint0/descriptors.h
index 8d494be6..46abddea 100644
--- a/module_usb_audio/endpoint0/descriptors.h
+++ b/module_usb_audio/endpoint0/descriptors.h
@@ -243,44 +243,32 @@ unsigned char devQualDesc_Null[] =
 
 
 // Positions in strDescs_Audio2
-#define INTERNAL_CLOCK_STRING_INDEX (14)
-#define SPDIF_CLOCK_STRING_INDEX    (15)
-
+enum {
+    INTERNAL_CLOCK_STRING_INDEX = 14,
 #ifdef SPDIF_RX
-#define ADAT_CLOCK_STRING_INDEX (SPDIF_CLOCK_STRING_INDEX + 1)
-#else
-#define ADAT_CLOCK_STRING_INDEX (SPDIF_CLOCK_STRING_INDEX)
+    SPDIF_CLOCK_STRING_INDEX,
 #endif
-
 #ifdef ADAT_RX
-#define DFU_STRING_INDEX (ADAT_CLOCK_STRING_INDEX + 1)
-#else
-#define DFU_STRING_INDEX (ADAT_CLOCK_STRING_INDEX)
+    ADAT_CLOCK_STRING_INDEX,
 #endif
-
 #ifdef DFU
-#define MIDI_OUT_STRING_INDEX (DFU_STRING_INDEX + 1)
-#else
-#define MIDI_OUT_STRING_INDEX (DFU_STRING_INDEX)
+    DFU_STRING_INDEX,
 #endif
-
-#define MIDI_IN_STRING_INDEX (MIDI_OUT_STRING_INDEX + 1)
-
 #ifdef MIDI
-#define OUTPUT_INTERFACE_STRING_INDEX (MIDI_OUT_STRING_INDEX + 2)
-#else
-#define OUTPUT_INTERFACE_STRING_INDEX (MIDI_OUT_STRING_INDEX)
+    MIDI_OUT_STRING_INDEX,
+    MIDI_IN_STRING_INDEX,
 #endif
-
-#define INPUT_INTERFACE_STRING_INDEX (OUTPUT_INTERFACE_STRING_INDEX + NUM_USB_CHAN_OUT)
-
-#define MIXER_STRING_INDEX (INPUT_INTERFACE_STRING_INDEX + NUM_USB_CHAN_IN)
-
+    OUTPUT_INTERFACE_STRING_INDEX,
+    OUTPUT_INTERFACE_LAST_STRING_INDEX = OUTPUT_INTERFACE_STRING_INDEX + NUM_USB_CHAN_OUT - 1,
+    INPUT_INTERFACE_STRING_INDEX,
+    INPUT_INTERFACE_LAST_STRING_INDEX = INPUT_INTERFACE_STRING_INDEX + NUM_USB_CHAN_IN - 1,
 #ifdef MIXER
-#define IAP_INTERFACE_STRING_INDEX (MIXER_STRING_INDEX + MAX_MIX_COUNT)
-#else
-#define IAP_INTERFACE_STRING_INDEX (MIXER_STRING_INDEX)
+    MIXER_STRING_INDEX,
 #endif
+#ifdef IAP
+    IAP_INTERFACE_STRING_INDEX,
+#endif
+};
 
 #ifdef HID_CONTROLS
 unsigned char hidReportDescriptor[] = {