diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e07b3e6d175..e371bf761cc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-17  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	* config/arm/arm.c (cmse_nonsecure_entry_clear_before_return): Allocate
+	to_clear_arg_regs_bitmap to the same size as to_clear_bitmap.
+
 2017-11-17  Richard Biener  <rguenther@suse.de>
 
 	* tree-ssa-pre.c (phi_translate_1): Remove redundant constant
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index db99303f3fb..106e3edce0d 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -25205,7 +25205,8 @@ cmse_nonsecure_entry_clear_before_return (void)
   if (padding_bits_to_clear != 0)
     {
       rtx reg_rtx;
-      auto_sbitmap to_clear_arg_regs_bitmap (R0_REGNUM + NUM_ARG_REGS);
+      int to_clear_bitmap_size = SBITMAP_SIZE ((sbitmap) to_clear_bitmap);
+      auto_sbitmap to_clear_arg_regs_bitmap (to_clear_bitmap_size);
 
       /* Padding bits to clear is not 0 so we know we are dealing with
 	 returning a composite type, which only uses r0.  Let's make sure that