diff --git a/lib_com/options.h b/lib_com/options.h
index ed11ab3cfe704cebeb596fc37f64fa9b7aca1a3a..117bbda11b296f828d588860ed3594436c77c7d0 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -102,6 +102,7 @@
 #define HARMONIZE_2537_SetTCXModeInfo                 /* FhG: Harmonize SetTCXModeInfo  - IVAS_VERSION OBVIOUSLY NOT FITTING FOR EVS - pipes not green */
 #define HARMONIZE_2537_GetTCXMaxenergyChange            /* FhG: Harmonize GetTCXMaxenergyChange */
 #define HARMONIZE_2508_InitTransientDetection          /* FhG: harmonize GetAttackForTCXDecision derivates for evs/ivas  */
+#define FIX_BASOP_2555_FRAMELEN_CALC                     /* FhG: BASOP issue 2555: Simplify (sub-)framelength calculation in ivas_mdct_core_tns_ns_fx() */
 
 /* #################### End BE switches ################################## */
 
diff --git a/lib_dec/ivas_mdct_core_dec_fx.c b/lib_dec/ivas_mdct_core_dec_fx.c
index 9dfdddda17ac93923852914e3f2242e0cfe40eee..61c4bf0ce36a45451877ca5986aecc1d7a65a5db 100644
--- a/lib_dec/ivas_mdct_core_dec_fx.c
+++ b/lib_dec/ivas_mdct_core_dec_fx.c
@@ -1510,7 +1510,11 @@ void ivas_mdct_core_tns_ns_fx(
     Word16 left_rect[CPE_CHANNELS];
     Word16 L_spec[CPE_CHANNELS];
     Word32 sns_int_scf_fx[FDNS_NPTS];
+#ifdef FIX_BASOP_2555_FRAMELEN_CALC
+    Word16 length;
+#else
     Word16 exp, length;
+#endif
 
     /* Initializations */
     sts = hCPE->hCoreCoder;
@@ -1525,6 +1529,34 @@ void ivas_mdct_core_tns_ns_fx(
     FOR( ch = 0; ch < CPE_CHANNELS; ch++ )
     {
         st = sts[ch];
+#ifdef FIX_BASOP_2555_FRAMELEN_CALC
+        IF( EQ_16( st->core, TCX_20_CORE ) )
+        {
+            nSubframes[ch] = 1;
+            move16();
+
+            L_frame_global[ch] = st->L_frame;
+            L_frameTCX_glob[ch] = st->hTcxDec->L_frameTCX;
+            L_spec[ch] = st->hTcxCfg->tcx_coded_lines;
+            move16();
+            move16();
+            move16();
+        }
+        ELSE
+        {
+            nSubframes[ch] = NB_DIV;
+            move16();
+
+            assert( nSubframes[ch] == 2 && "Unexpected value for nSubframes[ch], NB_DIV (expected to be 2)." );
+
+            L_frame_global[ch] = shr( st->L_frame, 1 );
+            L_frameTCX_glob[ch] = shr( st->hTcxDec->L_frameTCX, 1 );
+            L_spec[ch] = shr( st->hTcxCfg->tcx_coded_lines, 1 );
+            move16();
+            move16();
+            move16();
+        }
+#else
         IF( EQ_16( st->core, TCX_20_CORE ) )
         {
             nSubframes[ch] = 1;
@@ -1549,6 +1581,7 @@ void ivas_mdct_core_tns_ns_fx(
         move16();
         L_spec[ch] = shl( L_spec[ch], add( exp, 1 ) );
         move16();
+#endif
 
         test();
         test();