diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 74101039c9..f4857e32f3 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-16  Pierre Langlois  <pierre.langlois@arm.com>
+
+	* aarch64-tdep.c (aarch64_pseudo_read_value): Mark S register as
+	unavailable if invalid.
+
 2015-07-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	Revert the previous 6 commits:
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 2cecad0f85..cec4d3e9e4 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -2482,7 +2482,11 @@ aarch64_pseudo_read_value (struct gdbarch *gdbarch,
 
       v_regnum = AARCH64_V0_REGNUM + regnum - AARCH64_S0_REGNUM;
       status = regcache_raw_read (regcache, v_regnum, reg_buf);
-      memcpy (buf, reg_buf, S_REGISTER_SIZE);
+      if (status != REG_VALID)
+	mark_value_bytes_unavailable (result_value, 0,
+				      TYPE_LENGTH (value_type (result_value)));
+      else
+	memcpy (buf, reg_buf, S_REGISTER_SIZE);
       return result_value;
     }