diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index de76accd54..3460b3e2d6 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,3 +1,9 @@
+2019-12-11  Alan Modra  <amodra@gmail.com>
+
+	PR 25270
+	* aarch64-dis.c (aarch64_decode_variant_using_iclass): Return
+	false when field is zero for sve_size_tsz_bhs.
+
 2019-12-11  Alan Modra  <amodra@gmail.com>
 
 	* epiphany-ibld.c: Regenerate.
diff --git a/opcodes/aarch64-dis.c b/opcodes/aarch64-dis.c
index 9300569813..8b32097a5f 100644
--- a/opcodes/aarch64-dis.c
+++ b/opcodes/aarch64-dis.c
@@ -2843,6 +2843,8 @@ aarch64_decode_variant_using_iclass (aarch64_inst *inst)
 
     case sve_size_tsz_bhs:
       i = extract_fields (inst->value, 0, 2, FLD_SVE_sz, FLD_SVE_tszl_19);
+      if (i == 0)
+	return FALSE;
       while (i != 1)
 	{
 	  if (i & 1)