diff --git a/lib_com/options.h b/lib_com/options.h
index 10396a5c34071df32d355449d6e62d8717e547a8..9cc74f220b8c41aa41ce5b1b4ac91f4e282361df 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -108,6 +108,7 @@
 #define FIX_2283_ISM_MD_DELAY                           /* Dolby: Fix ISM metadata delay round-off */
 #define FIX_2283_Q_CLDFB                                /* FhG: Fix Q format issue in CLDFB */
 #define FIX_2283_ACCU_CLDFB                             /* FhG: Fix to consider Q-format differences in accumulateCLDFBArrayToBuffer_fx() */
+#define FIX_FLOAT_1533_BLEND_SUBFR2                     /* FhG: float issue 1533: correct blending in blend_subfr2() */
 
 /* ##################### End NON-BE switches ########################### */
 
diff --git a/lib_com/prot_fx.h b/lib_com/prot_fx.h
index a4a32366e6dc07bb41847717659e3d5eb48f0c2b..0ba1a3200e16c3891ed58f07ff29126ee8f30d08 100644
--- a/lib_com/prot_fx.h
+++ b/lib_com/prot_fx.h
@@ -6171,7 +6171,10 @@ void scale_st_fx(
 void blend_subfr2_fx(
     Word16 *sigIn1, /* i  : i   signal for fade-out */
     Word16 *sigIn2, /* i  : i   signal for fade-in  */
-    Word16 *sigOut  /* o  : output signal             */
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    Word16 L_subfr, /* i  : subframe length           */
+#endif
+    Word16 *sigOut /* o  : output signal             */
 );
 
 void init_tcx_window_cfg_fx(
diff --git a/lib_dec/acelp_core_dec_fx.c b/lib_dec/acelp_core_dec_fx.c
index 7b06d4b0d64a521878f81473c42df863e9c031f4..eefc304e31cfd7a654bfe751b51100cb885abddd 100644
--- a/lib_dec/acelp_core_dec_fx.c
+++ b/lib_dec/acelp_core_dec_fx.c
@@ -1529,7 +1529,11 @@ ivas_error acelp_core_dec_fx(
             E_UTIL_synthesis( 1, Aq_fx, temp_buf_fx + M + L_SUBFR, temp_buf_fx, L_SUBFR, st->hPFstat->mem_stp + L_SYN_MEM - M, 0, M );
             scale_st_fx( psyn_fx, temp_buf_fx, &st->hPFstat->gain_prec, L_SUBFR );
             Copy( temp_buf_fx, psyn_fx, ( L_SUBFR >> 1 ) );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            blend_subfr2_fx( temp_buf_fx + L_SUBFR / 2, psyn_fx + L_SUBFR / 2, L_SUBFR, psyn_fx + L_SUBFR / 2 );
+#else
             blend_subfr2_fx( temp_buf_fx + L_SUBFR / 2, psyn_fx + L_SUBFR / 2, psyn_fx + L_SUBFR / 2 );
+#endif
         }
         st->hPFstat->on = 0;
         move16();
diff --git a/lib_dec/acelp_core_switch_dec_fx.c b/lib_dec/acelp_core_switch_dec_fx.c
index dd477874f1de42f56209d021d5f2a4edca6a9cde..d4ccf00f9110d78a2b2de1dba819fd261974d4c2 100644
--- a/lib_dec/acelp_core_switch_dec_fx.c
+++ b/lib_dec/acelp_core_switch_dec_fx.c
@@ -177,7 +177,11 @@ ivas_error acelp_core_switch_dec_fx(
             E_UTIL_synthesis( 1, Aq, exc, bpf_error_signal, L_SUBFR, st_fx->hPFstat->mem_stp + L_SYN_MEM - M, 0, M );
             scale_st_fx( synth_intFreq, bpf_error_signal, &st_fx->hPFstat->gain_prec, L_SUBFR );
             Copy( bpf_error_signal, synth_intFreq, L_SUBFR / 2 );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            blend_subfr2_fx( bpf_error_signal + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2, L_SUBFR, synth_intFreq + L_SUBFR / 2 );
+#else
             blend_subfr2_fx( bpf_error_signal + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2 );
+#endif
         }
         st_fx->hPFstat->on = 0;
         move16();
diff --git a/lib_dec/dec_post_fx.c b/lib_dec/dec_post_fx.c
index 1a568cbf9a109fabc600841fc3ed3afab2f9aad7..442e0caf070b9015759f51d6f300120618ffba00 100644
--- a/lib_dec/dec_post_fx.c
+++ b/lib_dec/dec_post_fx.c
@@ -1513,18 +1513,41 @@ void scale_st_fx(
 void blend_subfr2_fx(
     Word16 *sigIn1, // Qx
     Word16 *sigIn2, // Qx
-    Word16 *sigOut  // Qx
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    Word16 L_subfr, // Q0
+#endif
+    Word16 *sigOut // Qx
 )
 {
     Word16 fac1 = 32768 - 512; // 1.Q15 - ( 1.Q15 / L_SUBFR );
     Word16 fac2 = 0 + 512;     // 0.Q15 + ( 1.Q15 / L_SUBFR );
     Word16 step = 1024;        // 1.Q15 / ( L_SUBFR / 2 );
-    Word16 i;
+    Word16 i, L_subfr_half;
     move16();
     move16();
     move16();
 
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    assert( ( L_subfr == L_SUBFR ) || ( L_subfr == 2 * L_SUBFR ) );
+
+    IF( EQ_16( L_subfr, 2 * L_SUBFR ) )
+    {
+        fac1 = 32768 - 256; // 1.Q15 - ( 1.Q15 / L_SUBFR );
+        fac2 = 0 + 256;     // 0.Q15 + ( 1.Q15 / L_SUBFR );
+        step = 512;         // 1.Q15 / ( L_SUBFR / 2 );
+        move16();
+        move16();
+        move16();
+    }
+#endif
+
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    L_subfr_half = shr( L_subfr, 1 );
+
+    FOR( i = 0; i < L_subfr_half; i++ )
+#else
     FOR( i = 0; i < L_SUBFR / 2; i++ )
+#endif
     {
         sigOut[i] = mac_r_sat( L_mult_sat( fac1, sigIn1[i] ), fac2, sigIn2[i] ); // Qx
         fac1 = sub_sat( fac1, step );
diff --git a/lib_dec/post_dec_fx.c b/lib_dec/post_dec_fx.c
index 8bf9380b3fbe89ad809c452874a919b35cb61be8..6f00fd72047c3730de341bcbbf410b30e5b0866a 100644
--- a/lib_dec/post_dec_fx.c
+++ b/lib_dec/post_dec_fx.c
@@ -75,7 +75,11 @@ void post_decoder(
             Residu3_fx( st->old_Aq_12_8_fx, synth, synth_buf, L_SUBFR, 1 );
             E_UTIL_synthesis( 1, st->old_Aq_12_8_fx, synth_buf, synth2, L_SUBFR, st->hPFstat->mem_stp + L_SYN_MEM - M, 0, M );
             scale_st_fx( synth, synth2, &st->hPFstat->gain_prec, L_SUBFR );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            blend_subfr2_fx( synth2 + L_SUBFR / 2, synth + L_SUBFR / 2, L_SUBFR, synth2 + L_SUBFR / 2 );
+#else
             blend_subfr2_fx( synth2 + L_SUBFR / 2, synth + L_SUBFR / 2, synth2 + L_SUBFR / 2 );
+#endif
         }
     }
     ELSE
@@ -238,7 +242,18 @@ void post_decoder_ivas_fx(
             Residu3_fx( st->old_Aq_12_8_fx, synth, synth_buf, L_subfr, 1 );
             E_UTIL_synthesis( 1, st->old_Aq_12_8_fx, synth_buf, synth2, L_subfr, st->hPFstat->mem_stp + L_SYN_MEM - M, 0, M );
             scale_st_fx( synth, synth2, &st->hPFstat->gain_prec, L_subfr );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            IF( EQ_16( st->element_mode, EVS_MONO ) )
+            {
+                blend_subfr2_fx( synth2 + shr( L_subfr, 1 ), synth + shr( L_subfr, 1 ), L_SUBFR, synth2 + shr( L_subfr, 1 ) );
+            }
+            ELSE
+            {
+                blend_subfr2_fx( synth2 + shr( L_subfr, 1 ), synth + shr( L_subfr, 1 ), L_subfr, synth2 + shr( L_subfr, 1 ) );
+            }
+#else
             blend_subfr2_fx( synth2 + shr( L_subfr, 1 ), synth + shr( L_subfr, 1 ), synth2 + shr( L_subfr, 1 ) );
+#endif
         }
     }
     ELSE