diff --git a/lib_com/options.h b/lib_com/options.h
index 64354c999c48f4ea907f89e0e860b0ce39de6e07..c0d07582cca1bb43820bf56e3abbd52c45bfad8e 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -96,6 +96,7 @@
 #define FIX_FLOAT_1600_OMASA_WRONG_RENDER_PATH          /* Nokia: float issue 1600: fix initialization condition of stereo type detection for OMASA */
 #define FIX_BASOP_2627_PARAM_MC_ILD_REMAP_EXP           /* FhG: BASOP #2627: accumulate 10^(ILD/10) using a dynamic exponent */
 #define FIX_BASOP_2635_EFAP_ADD_VERTEX_ELE_ROUND        /* FhG: BASOP #2635: round |elevation| with anint_fx before the 90deg subtraction in add_vertex_fx */
+#define FIX_BASOP_2639_INCORRECT_ARRAY_INDEX            /* Dolby: BASOP #2639: incorrect array index in ivas_spar_unquant_dtx_indicies */
 
 /* ##################### End NON-BE switches ########################### */
 
diff --git a/lib_dec/ivas_spar_md_dec_fx.c b/lib_dec/ivas_spar_md_dec_fx.c
index 13befdb33cc1b8ddde94bcd4ea8447cf689dc325..c40807693e8a72fe9a9c21688fc0ae1d6c6ba995 100644
--- a/lib_dec/ivas_spar_md_dec_fx.c
+++ b/lib_dec/ivas_spar_md_dec_fx.c
@@ -2618,7 +2618,11 @@ static void ivas_spar_unquant_dtx_indicies(
             move32();
         }
 
+#ifdef FIX_BASOP_2639_INCORRECT_ARRAY_INDEX
+        FOR( i = 0; i < ( FOA_CHANNELS - ndm_per_band[( bw * b )] ); i++ )
+#else
         FOR( i = 0; i < ( FOA_CHANNELS - ndm_per_band[( bw - b )] ); i++ )
+#endif
         {
             q_lvl = dtx_pd_real_q_levels[( ndm_per_band[( bw * b )] - 1 )][i]; /*Q0*/
             move16();