diff --git a/lib_com/ivas_cnst.h b/lib_com/ivas_cnst.h
index 097ba1789fbbe33cb9dd648fef5a97f070b98805..d3e52ec16775dd7abbb033a08b3a2801f65e77a6 100644
--- a/lib_com/ivas_cnst.h
+++ b/lib_com/ivas_cnst.h
@@ -383,7 +383,7 @@ typedef enum
 #define PARAM_ISM_MAX_CHAN                      16
 #define PARAM_ISM_HYS_BUF_SIZE                  10
 
-#define STEP_PARAM_ISM_POW_RATIO_NBITS_Q15      (4681)  /* 1.0f / (float)((1 << PARAM_ISM_POW_RATIO_NBITS) - 1) */
+#define STEP_PARAM_ISM_POW_RATIO_NBITS_Q31      (306783378)  /* 1.0f / (float)((1 << PARAM_ISM_POW_RATIO_NBITS) - 1) */
 
 /* ISM DTX */
 #define ISM_Q_STEP_FX                           ( 10485760 )  // Q22
diff --git a/lib_com/ivas_masa_com_fx.c b/lib_com/ivas_masa_com_fx.c
index cfed06357fe908e6c3fda28720aa7272ca67adb0..a691fb390380b8f2f12c1510fcf719432fc09d25 100644
--- a/lib_com/ivas_masa_com_fx.c
+++ b/lib_com/ivas_masa_com_fx.c
@@ -1308,7 +1308,7 @@ Word16 valid_ratio_index_fx(
 void reconstruct_ism_ratios_fx(
     Word16 *ratio_ism_idx,     /* i  : index vector                 Q0  */
     const Word16 nchan_ism,    /* i  : number of components/objects Q0  */
-    const Word16 step,         /* i  : quantization step            Q15 */
+    const Word32 step,         /* i  : quantization step            Q31 */
     Word32 *q_energy_ratio_ism /* o  : reconstructed ISM values     Q30 */
 )
 {
@@ -1320,7 +1320,7 @@ void reconstruct_ism_ratios_fx(
 
     FOR( i = 0; i < nchan_ism - 1; i++ )
     {
-        q_energy_ratio_ism[i] = L_shl( L_mult( ratio_ism_idx[i], step ), 14 ); // q0 + q15 + 1 + 14 = q30;
+        q_energy_ratio_ism[i] = W_extract_l( W_shr( W_mult_32_16( step, ratio_ism_idx[i] ), 2 ) ); // q0 + q31 + 1 - 2 = q30;
         move32();
 
         sum = L_add( sum, q_energy_ratio_ism[i] ); // Q30
diff --git a/lib_com/ivas_prot_fx.h b/lib_com/ivas_prot_fx.h
index d9ca855be51c5a2e033c63e0ae19db1b8095c625..542f9e0e90d6e2da8ea724358db8f34f0544bd64 100644
--- a/lib_com/ivas_prot_fx.h
+++ b/lib_com/ivas_prot_fx.h
@@ -115,7 +115,7 @@ ivas_error ivas_masa_dec_reconfigure_fx(
 void reconstruct_ism_ratios_fx(
     Word16 *ratio_ism_idx,     /* i  : index vector                 Q0  */
     const Word16 nchan_ism,    /* i  : number of components/objects Q0  */
-    const Word16 step,         /* i  : quantization step            Q15 */
+    const Word32 step,         /* i  : quantization step            Q31 */
     Word32 *q_energy_ratio_ism /* o  : reconstructed ISM values     Q30 */
 );
 
diff --git a/lib_dec/ivas_masa_dec_fx.c b/lib_dec/ivas_masa_dec_fx.c
index 36900867e47fe247992d9177597001a1312e22e8..e61e51262c6392dfaaed7cec42e11370d725b44f 100644
--- a/lib_dec/ivas_masa_dec_fx.c
+++ b/lib_dec/ivas_masa_dec_fx.c
@@ -3097,7 +3097,7 @@ static void decode_ism_ratios_fx(
         /* reconstructed values */
         FOR( band = 0; band < nbands; band++ )
         {
-            reconstruct_ism_ratios_fx( ratio_ism_idx[band], n_ism, STEP_PARAM_ISM_POW_RATIO_NBITS_Q15, ratio_ism[sf][band] );
+            reconstruct_ism_ratios_fx( ratio_ism_idx[band], n_ism, STEP_PARAM_ISM_POW_RATIO_NBITS_Q31, ratio_ism[sf][band] );
         }
 
         test();
diff --git a/lib_enc/ivas_masa_enc_fx.c b/lib_enc/ivas_masa_enc_fx.c
index 303d11698f6a139708f17cb47aa39543bcfddd56..fb86dee7a431a079183be1c31c0a5a9e86fb7d18 100644
--- a/lib_enc/ivas_masa_enc_fx.c
+++ b/lib_enc/ivas_masa_enc_fx.c
@@ -4666,7 +4666,6 @@ static void ivas_encode_masaism_metadata_fx(
     UWord16 index_theta, index_phi;
     Word16 ratio_ism_fx[MASA_FREQUENCY_BANDS][MAX_NUM_OBJECTS];
     Word16 ratio_ism_idx[MASA_FREQUENCY_BANDS][MAX_NUM_OBJECTS], ratio_ism_idx_prev_sf[MASA_FREQUENCY_BANDS][MAX_NUM_OBJECTS];
-    Word16 step;
     Word32 energy_ism, energy_ism_ind[MAX_NUM_OBJECTS];
     Word16 tmp, rotate, energy_ism_e, energy_ism_ind_e[MAX_NUM_OBJECTS];
     Word16 n_ism_tmp, i;
@@ -4919,11 +4918,6 @@ static void ivas_encode_masaism_metadata_fx(
     /* quantize ism_ratios */
     IF( GT_16( nchan_ism, 1 ) )
     {
-        /* inv_step = ( ( 1 << PARAM_ISM_POW_RATIO_NBITS ) - 1 ); *
-         * step = 1.0f / inv_step;                                */
-        step = 4681; // 1.f / ( ( 1 << PARAM_ISM_POW_RATIO_NBITS ) - 1 ) => 1.f / 7 in Q15
-        move16();
-
         rotate = 0;
         n_ism_tmp = 0;
         move16();
@@ -4968,7 +4962,7 @@ static void ivas_encode_masaism_metadata_fx(
                 }
 
                 /* reconstructed values */
-                reconstruct_ism_ratios_fx( ratio_ism_idx[band], nchan_ism, step, hMasa->data.hOmasaData->q_energy_ratio_ism_fx[sf][band] );
+                reconstruct_ism_ratios_fx( ratio_ism_idx[band], nchan_ism, STEP_PARAM_ISM_POW_RATIO_NBITS_Q31, hMasa->data.hOmasaData->q_energy_ratio_ism_fx[sf][band] );
             }
             test();
             IF( GT_16( nchan_ism, 2 ) && EQ_16( idx_separated_object, sub( nchan_ism, 1 ) ) )