diff --git a/src/bspline_sub_module.f90 b/src/bspline_sub_module.f90
index 145f210..37ff162 100644
--- a/src/bspline_sub_module.f90
+++ b/src/bspline_sub_module.f90
@@ -58,6 +58,9 @@ end function b1fqad_func
     end interface
     public :: b1fqad_func
 
+    integer(ip),parameter,public :: bspline_order_linear    = 2_ip !! spline order `k` parameter
+                                                                   !! (for input to the `db*ink` routines)
+                                                                   !! [order = polynomial degree + 1]
     integer(ip),parameter,public :: bspline_order_quadratic = 3_ip !! spline order `k` parameter
                                                                    !! (for input to the `db*ink` routines)
                                                                    !! [order = polynomial degree + 1]
diff --git a/test/bspline_linear_test.f90 b/test/bspline_linear_test.f90
index fbb474b..26064ef 100644
--- a/test/bspline_linear_test.f90
+++ b/test/bspline_linear_test.f90
@@ -39,11 +39,11 @@ program bspline_linear_test
     iloy  = 1
 
     ! initialize
-    call b2%initialize(x,fcn_1d,2,iflag,extrap=.true.) ! linear
+    call b2%initialize(x,fcn_1d,bspline_order_linear,iflag,extrap=.true.) ! linear
     if (iflag/=0) error stop 'Error initializing 1D linear spline: '//get_status_message(iflag)
-    call b3%initialize(x,fcn_1d,3,iflag,extrap=.true.) ! quadratic
+    call b3%initialize(x,fcn_1d,bspline_order_quadratic,iflag,extrap=.true.) ! quadratic
     if (iflag/=0) error stop 'Error initializing 1D quadratic spline: '//get_status_message(iflag)
-    call b4%initialize(x,fcn_1d,4,iflag,extrap=.true.) ! cubic
+    call b4%initialize(x,fcn_1d,bspline_order_cubic,iflag,extrap=.true.) ! cubic
     if (iflag/=0) error stop 'Error initializing 1D cubic spline: '//get_status_message(iflag)
     call s1%initialize(x,fcn_1d,iflag)
     if (iflag/=0) error stop 'Error initializing 1D linear interpolator'