diff --git a/lib_com/calc_st_com.c b/lib_com/calc_st_com.c
index 60271a77d57b25755c9ef1fb66ceea0e476b5890..62e0e808047eb5d099dca3b3b51ebf2bb438fb41 100644
--- a/lib_com/calc_st_com.c
+++ b/lib_com/calc_st_com.c
@@ -292,14 +292,27 @@ void scale_st(
 void blend_subfr2(
     float *sigIn1,
     float *sigIn2,
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    int16_t L_subfr,
+#endif
     float *sigOut )
 {
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    float fac1 = 1.f - ( 1.f / L_subfr );
+    float fac2 = 0.f + ( 1.f / L_subfr );
+    float step = 1.f / ( L_subfr / 2 );
+#else
     float fac1 = 1.f - ( 1.f / L_SUBFR );
     float fac2 = 0.f + ( 1.f / L_SUBFR );
     float step = 1.f / ( L_SUBFR / 2 );
+#endif
     int16_t i;
 
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    for ( i = 0; i < L_subfr / 2; i++ )
+#else
     for ( i = 0; i < L_SUBFR / 2; i++ )
+#endif
     {
         sigOut[i] = fac1 * sigIn1[i] + fac2 * sigIn2[i];
         fac1 -= step;
diff --git a/lib_com/options.h b/lib_com/options.h
index c0cd3fbb39c3b43142a16560c6a5f78e3881be31..7d7d95965dacd6c9a6f76f795b0a2a1b0f5a7b9d 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -173,6 +173,7 @@
 
 #define FIX_2432_ISM_SPIKES_16KHZ                       /* VA: basop issue 2432: fix spikes in ISM decoding at 16kHz output sampling rate */
 #define FIX_FLOAT_1518                                  /* FhG: fix issue 1518: loudness differences in OSBA decoding to mono or stereo output */
+#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.h b/lib_com/prot.h
index 55453a263f42930fa70e7c43c8fe59df5161177e..dd3a1c48f4ac6725b0f2ac5c1e87df2985ae93aa 100644
--- a/lib_com/prot.h
+++ b/lib_com/prot.h
@@ -10045,7 +10045,10 @@ int16_t tbe_celp_exc_offset(
 void blend_subfr2(
     float *sigIn1, /* i  : input signal for fade-out */
     float *sigIn2, /* i  : input signal for fade-in  */
-    float *sigOut  /* o  : output signal             */
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+    int16_t L_subfr, /* i  : subframe length           */
+#endif
+    float *sigOut /* o  : output signal             */
 );
 
 void init_tcx_window_cfg(
diff --git a/lib_dec/acelp_core_dec.c b/lib_dec/acelp_core_dec.c
index bafbba55351854a720cac5ea31a212fa6bc82be1..a952efd5d224a59c0708559b2536686bfae5ccf2 100644
--- a/lib_dec/acelp_core_dec.c
+++ b/lib_dec/acelp_core_dec.c
@@ -1091,7 +1091,11 @@ ivas_error acelp_core_dec(
             syn_filt( Aq, M, temp_buf + M + L_SUBFR, temp_buf, L_SUBFR, st->hPFstat->mem_stp + L_SYN_MEM - M, 0 );
             scale_st( syn, temp_buf, &st->hPFstat->gain_prec, L_SUBFR, -1 );
             mvr2r( temp_buf, syn, L_SUBFR / 2 );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            blend_subfr2( temp_buf + L_SUBFR / 2, syn + L_SUBFR / 2, L_SUBFR, syn + L_SUBFR / 2 );
+#else
             blend_subfr2( temp_buf + L_SUBFR / 2, syn + L_SUBFR / 2, syn + L_SUBFR / 2 );
+#endif
         }
         st->hPFstat->on = 0;
     }
diff --git a/lib_dec/acelp_core_switch_dec.c b/lib_dec/acelp_core_switch_dec.c
index b32df0c6dd3f68df0db629ef07c2bea196dee6dd..d40d7def7cb48e0ea821987399d192c6c2fda098 100644
--- a/lib_dec/acelp_core_switch_dec.c
+++ b/lib_dec/acelp_core_switch_dec.c
@@ -201,7 +201,11 @@ ivas_error acelp_core_switch_dec(
             syn_filt( Aq, M, old_exc, bpf_error_signal, L_SUBFR, st->hPFstat->mem_stp + L_SYN_MEM - M, 0 );
             scale_st( synth_intFreq, bpf_error_signal, &st->hPFstat->gain_prec, L_SUBFR, -1 );
             mvr2r( bpf_error_signal, synth_intFreq, L_SUBFR / 2 );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            blend_subfr2( bpf_error_signal + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2, L_SUBFR, synth_intFreq + L_SUBFR / 2 );
+#else
             blend_subfr2( bpf_error_signal + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2, synth_intFreq + L_SUBFR / 2 );
+#endif
         }
         st->hPFstat->on = 0;
 
diff --git a/lib_dec/post_dec.c b/lib_dec/post_dec.c
index c119770f7b9f232e8e59ff5b8001350dd73f9633..35d8dae700d472164487cf0ed5541a5a05aa5caa 100644
--- a/lib_dec/post_dec.c
+++ b/lib_dec/post_dec.c
@@ -109,7 +109,18 @@ void post_decoder(
             residu( A, M, synth, synth_buf, L_subfr );
             syn_filt( A, M, synth_buf, synth2, L_subfr, st->hPFstat->mem_stp + L_SYN_MEM - M, 0 );
             scale_st( synth, synth2, &st->hPFstat->gain_prec, L_subfr, -1 );
+#ifdef FIX_FLOAT_1533_BLEND_SUBFR2
+            if ( st->element_mode == EVS_MONO )
+            {
+                blend_subfr2( synth2 + L_subfr / 2, synth + L_subfr / 2, L_SUBFR, synth2 + L_subfr / 2 );
+            }
+            else
+            {
+                blend_subfr2( synth2 + L_subfr / 2, synth + L_subfr / 2, L_subfr, synth2 + L_subfr / 2 );
+            }
+#else
             blend_subfr2( synth2 + L_subfr / 2, synth + L_subfr / 2, synth2 + L_subfr / 2 );
+#endif
         }
     }
     else