diff --git a/src/odrpack_core.f90 b/src/odrpack_core.f90
index 2c6facb..0e5712a 100644
--- a/src/odrpack_core.f90
+++ b/src/odrpack_core.f90
@@ -4740,9 +4740,7 @@ subroutine dodstp &
       ! Do QR factorization (with column pivoting of TFJACB if ALPHA = 0)
       if (alpha == zero) then
          ipvt = 1
-         do k = 1, np
-            kpvt(k) = 0
-         end do
+         kpvt(1:np) = 0
       else
          ipvt = 0
       end if