diff --git a/src/audio/SDL_wave.c b/src/audio/SDL_wave.c
index b1bd0538c..18fdcacd3 100644
--- a/src/audio/SDL_wave.c
+++ b/src/audio/SDL_wave.c
@@ -273,6 +273,11 @@ IMA_ADPCM_nibble(struct IMA_ADPCM_decodestate *state, Uint8 nybble)
     Sint32 delta, step;
 
     /* Compute difference and new sample value */
+    if (state->index > 88) {
+        state->index = 88;
+    } else if (state->index < 0) {
+        state->index = 0;
+    }
     step = step_table[state->index];
     delta = step >> 3;
     if (nybble & 0x04)
@@ -287,11 +292,6 @@ IMA_ADPCM_nibble(struct IMA_ADPCM_decodestate *state, Uint8 nybble)
 
     /* Update index value */
     state->index += index_table[nybble];
-    if (state->index > 88) {
-        state->index = 88;
-    } else if (state->index < 0) {
-        state->index = 0;
-    }
 
     /* Clamp output sample */
     if (state->sample > max_audioval) {