diff --git a/lib_com/options.h b/lib_com/options.h
index 8e0fe3db46db84b8a64e4f5f1256085355e7e90d..c5fa1d384f0a1fc371c6945452ad194a27a4a990 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -147,6 +147,7 @@
 /*#define FIX_IVAS_180_PLC_SIGNAL_LAST_OVLP_IN_TCX10*/  /* IVAS-180 write last overlap mode in TCX10 frames to allow for correct TCX10/TCX5 subframe decomposition in TCX10 frames after a lost frame */
 /*#define FIX_I1_113*/                                  /* under review : MCT bit distribution optimization for SBA high bitrates*/
 
+#define FIX_1_CUSTOM_LS                                   /* fix bug 1-ivas-internal-error-in-decoder-for-custom-loudspeaker-format-with-sba-input-at-24-4kbps */
 #define FIX_TDREND_STANDALONE                           /* Fix for TD standalone renderer (broken after update of hHrtfTD pointer and addition of hRenderConfig */
 
 /* ################## End DEVELOPMENT switches ######################### */
diff --git a/lib_dec/ivas_spar_foa_dec.c b/lib_dec/ivas_spar_foa_dec.c
index 1adcc883d4b7cce97378fa9e7b17d85d375b74f4..0a2a61c83ed5a6731d137fbac50865a984630968 100644
--- a/lib_dec/ivas_spar_foa_dec.c
+++ b/lib_dec/ivas_spar_foa_dec.c
@@ -976,7 +976,11 @@ void ivas_spar_foa_dec_upmixer(
     /* determine if we can skip certain data */
     ivas_spar_get_skip_mat( hSparFoa, numch_out, numch_in, num_spar_bands, b_skip_mat ); /* this can be precomputed based on bitrate and format*/
 
+#ifdef FIX_1_CUSTOM_LS
+    numch_out_dirac = st_ivas->hDecoderConfig->nchan_out;
+#else
     numch_out_dirac = audioCfg2channels( st_ivas->hDecoderConfig->output_config );
+#endif
 
     for ( int16_t i_sf = 0; i_sf < MAX_PARAM_SPATIAL_SUBFRAMES; i_sf++ )
     {