diff --git a/lib_dec/ivas_stereo_mdct_core_dec_fx.c b/lib_dec/ivas_stereo_mdct_core_dec_fx.c
index 79b88b88c159b8abd89d124905291c75ed722512..afcc6ab60a9dc8560d65ddd1286e0875f3a04876 100644
--- a/lib_dec/ivas_stereo_mdct_core_dec_fx.c
+++ b/lib_dec/ivas_stereo_mdct_core_dec_fx.c
@@ -1043,25 +1043,29 @@ static void run_min_stats_fx(
             IF( ( EQ_16( will_estimate_noise_on_channel[0], will_estimate_noise_on_channel[1] ) ) || EQ_16( ch, 0 ) )
             {
                 Word16 tmp16 = getScaleFactor32( spec_in, L_FRAME16k );
-
+                Word64 spec_power;
                 Word32 power_spec_scale_fac;
 
                 /* calculate power spectrum from MDCT coefficients and estimated MDST coeffs */
-                power_spec_scale_fac = 20792; // 1.f / ( L_FRAME16k * L_FRAME16k ) in Q31
-                move32();
-                power_spec[0] = Mpy_32_32( W_extract_h( W_shl( W_mult_32_32( spec_in[0], spec_in[0] ), sub( tmp16, 4 ) ) ), power_spec_scale_fac ); /* 2 * (Q31 - x_e) + tmp16 - Q4 - Q31 */
+                power_spec_scale_fac = 20792; /* 1.f / ( L_FRAME16k * L_FRAME16k ) in Q31 */
+
+                spec_power = W_shl( W_mult_32_32( spec_in[0], spec_in[0] ), 2 * tmp16 );
+                power_spec[0] = W_extract_l( W_shr( W_mult_32_32( W_extract_h( spec_power ), power_spec_scale_fac ), 16 ) ); /* 2 * (Q31 - x_e + tmp16) + 1 - Q16 */
                 move32();
-                power_spec[L_FRAME16k - 1] = Mpy_32_32( W_extract_h( W_shl( W_mult_32_32( spec_in[L_FRAME16k - 1], spec_in[L_FRAME16k - 1] ), sub( tmp16, 4 ) ) ), power_spec_scale_fac ); /* 2 * (Q31 - x_e) + tmp16 - Q4 - Q31 */
+
+                spec_power = W_shl( W_mult_32_32( spec_in[L_FRAME16k - 1], spec_in[L_FRAME16k - 1] ), 2 * tmp16 );
+                power_spec[L_FRAME16k - 1] = W_extract_l( W_shr( W_mult_32_32( W_extract_h( spec_power ), power_spec_scale_fac ), 16 ) ); /* 2 * (Q31 - x_e + tmp16) + 1 - Q16 */
                 move32();
+
                 FOR( Word16 i = 1; i < L_FRAME16k - 1; i++ )
                 {
                     Word32 mdst;
                     mdst = L_sub( spec_in[i + 1], spec_in[i - 1] ); /* Q31 - x_e */
-
-                    power_spec[i] = Mpy_32_32( L_add( W_extract_h( W_shl( W_mult_32_32( spec_in[i], spec_in[i] ), sub( tmp16, 4 ) ) ), W_extract_h( W_shl( W_mult_32_32( mdst, mdst ), sub( tmp16, 4 ) ) ) ), power_spec_scale_fac ); /* 2 * (Q31 - x_e) + tmp16 - Q4 - Q31*/
+                    spec_power = W_shl( W_add( W_mult_32_32( spec_in[i], spec_in[i] ), W_mult_32_32( mdst, mdst ) ), 2 * tmp16 );
+                    power_spec[i] = W_extract_l( W_shr( W_mult_32_32( W_extract_h( spec_power ), power_spec_scale_fac ), 16 ) ); /* 2 * (Q31 - x_e + tmp16) + 1 - Q16 */
                     move32();
                 }
-                power_spec_e = sub( add( 4, shl( spec_e, 1 ) ), tmp16 );
+                power_spec_e = 2 * ( 31 - spec_e + tmp16 ) + 1 - 16;
             }
         }
 
@@ -1091,7 +1095,7 @@ static void run_min_stats_fx(
             {
                 arr_tmp = power_spec;
             }
-            ApplyFdCng_ivas_fx( NULL, 0, arr_tmp, sub( 31, power_spec_e ), NULL, NULL, NULL, st, st->bfi, 0 );
+            ApplyFdCng_ivas_fx( NULL, 0, arr_tmp, power_spec_e, NULL, NULL, NULL, st, st->bfi, 0 );
             /*=================================================*/
         }