diff --git a/lib_com/options.h b/lib_com/options.h
index 73144fdac51afb79de7dee7460e2f373040ea88e..4f498c158b61651d7d5c297575564e0ceefc88f0 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -141,4 +141,6 @@
 
 #define FIX_1818_WRONG_PIT_INIT                 /* VA: Fix wrong pitch initialization */
 
+#define NONBE_FIX_TCX5_INTERLEAVING_FOR_FS_IN_UNEQUAL_FS_OUT /* FhG: apply correct TCX5 grouping/interleaving when input_fs != output_fs */
+
 #endif
diff --git a/lib_dec/dec_tcx_fx.c b/lib_dec/dec_tcx_fx.c
index a35db1f8ec9511e82706ae8f0ff95ad005bba7cd..8009c69e011123ec9161741f2c1d18379e427e18 100644
--- a/lib_dec/dec_tcx_fx.c
+++ b/lib_dec/dec_tcx_fx.c
@@ -5646,7 +5646,12 @@ void decoder_tcx_tns_fx(
         test();
         test();
         test();
+#ifdef NONBE_FIX_TCX5_INTERLEAVING_FOR_FS_IN_UNEQUAL_FS_OUT
+        test();
+        IF( ( NE_16( hTcxCfg->fIsTNSAllowed, 0 ) && NE_16( fUseTns, 0 ) && NE_16( bfi, 1 ) && whitenedDomain ) || GT_16( L_spec, L_frameTCX ) )
+#else
         IF( ( NE_16( hTcxCfg->fIsTNSAllowed, 0 ) && NE_16( fUseTns, 0 ) && NE_16( bfi, 1 ) ) || GT_16( L_spec, L_frameTCX ) )
+#endif
         {
             L = L_spec;
             move16();
@@ -5700,7 +5705,12 @@ void decoder_tcx_tns_fx(
         IF( EQ_16( L_frame, shr( st->L_frame, 1 ) ) && st->tcxonly != 0 && isTCX5 != 0 )
         {
             test();
+#ifdef NONBE_FIX_TCX5_INTERLEAVING_FOR_FS_IN_UNEQUAL_FS_OUT
+            test();
+            IF( st->element_mode == EVS_MONO || ( LT_16( L_spec, L_frameTCX ) && !whitenedDomain ) ) /* todo: this is temporary to maintain EVS BE, this is a bug and should be fixed also for EVS (see issue 13) */
+#else
             IF( st->element_mode == EVS_MONO || LT_16( L_spec, L_frameTCX ) ) /* todo: this is temporary to maintain EVS BE, this is a bug and should be fixed also for EVS (see issue 13) */
+#endif
             {
                 tcx5TnsUngrouping_fx( shr( L_frameTCX, 1 ), shr( hTcxCfg->tnsConfig[0][0].iFilterBorders[0], 1 ), x_fx, DEC );
                 tmp = L_frameTCX;