diff --git a/lib_com/cnst.h b/lib_com/cnst.h
index 792df39463447c2de840230c79049d8b188e3334..53032d5aeae9b266126968ab19d81ea76c8690e7 100644
--- a/lib_com/cnst.h
+++ b/lib_com/cnst.h
@@ -134,7 +134,7 @@
 #define ONE_IN_Q29                      536870912
 #define ONE_IN_Q30                      1073741824
 #define ONE_IN_Q31                      0x7fffffff
-#define MINUS_ONE_IN_Q31                      -2147483648
+#define MINUS_ONE_IN_Q31                0x80000000
 #define TWO_IN_Q29                      1073741824
 #define FOUR_IN_Q28                     1073741824
 
diff --git a/lib_dec/dec_tcx_fx.c b/lib_dec/dec_tcx_fx.c
index 6206577c104b4fa833b3a00f1aa3cc10a198addb..643d8bf7d4821f977a3981c8ef29bb86b81735e8 100644
--- a/lib_dec/dec_tcx_fx.c
+++ b/lib_dec/dec_tcx_fx.c
@@ -5782,6 +5782,7 @@ void decoder_tcx_imdct_fx(
     move16();
 #ifdef FIX_1348_BIT_PRECISION_IMPROVEMENT_QWIN
     Word16 q_acelp_zir_fx = 0;
+    set16_fx( acelp_zir_fx, 0, L_FRAME_MAX / 2 );
 #else
     Word16 shift_q = sub( q_x, q_win );
 #endif
diff --git a/lib_dec/ivas_mdct_core_dec_fx.c b/lib_dec/ivas_mdct_core_dec_fx.c
index 92511a62dc71e7b6f00c5025d9d9f621e0d3f5aa..2baa31d22db37abfd1f956256654a4c820577083 100644
--- a/lib_dec/ivas_mdct_core_dec_fx.c
+++ b/lib_dec/ivas_mdct_core_dec_fx.c
@@ -1233,7 +1233,10 @@ void ivas_mdct_core_reconstruct_fx(
         IF( st->core != ACELP_CORE )
         {
 #ifdef FIX_1348_BIT_PRECISION_IMPROVEMENT_QWIN
-            Word16 q_win0, q_winFB0;
+            Word16 q_win0 = Q15;
+            move16();
+            Word16 q_winFB0 = Q15;
+            move16();
 #else
             Scale_sig( st->hTcxDec->syn_Overl_TDACFB, L_FRAME_MAX / 2, sub( q_win, st->hTcxDec->Q_syn_Overl_TDACFB ) ); // st->hTcxDec->Q_syn_Overl_TDACFB -> q_win
             st->hTcxDec->Q_syn_Overl_TDACFB = q_win;