diff --git a/GNUmakefile b/GNUmakefile
index 0d3d75ac6fa56e5322098915b3f3eaec4c0669b3..425e7f469de8d98c645b14dd9b54ce11377ffb97 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -17,7 +17,7 @@ src_test_set_all_outerm = test_set_all_outerm.f derived_types.f set_all_outerm.f
 
 src_test_weight = test_weight.f weight.f derived_types.f
 
-sources := $(sort ${src_test_local_extrema} ${src_test_get_1_outerm} ${src_test_set_max_speed} ${src_test_get_snapshot} ${src_test_set_all_outerm} ${src_test_weight}) test_good_contour.f test_inside_4.f test_max_speed_contour_ssh.f test_mean_speed.f
+sources := $(sort ${src_test_local_extrema} ${src_test_get_1_outerm} ${src_test_set_max_speed} ${src_test_get_snapshot} ${src_test_set_all_outerm} ${src_test_weight}) test_good_contour.f test_inside_4.f test_max_speed_contour_ssh.f test_mean_speed.f test_spherical_polyline_area.f
 
 lib_list = contour_531 numer_rec_95 shapelib_03 netcdf95 geometry jumble netcdff fortrangis shp fortranc nr_util
 
@@ -31,7 +31,7 @@ obj_test_set_all_outerm := $(src_test_set_all_outerm:.f=.o)
 obj_test_weight := $(src_test_weight:.f=.o)
 objects := $(sources:.f=.o)
 
-execut = test_good_contour test_inside_4 test_get_1_outerm test_local_extrema test_max_speed_contour_ssh test_mean_speed test_set_max_speed test_get_snapshot test_set_all_outerm test_weight
+execut = test_good_contour test_inside_4 test_get_1_outerm test_local_extrema test_max_speed_contour_ssh test_mean_speed test_set_max_speed test_get_snapshot test_set_all_outerm test_weight test_spherical_polyline_area
 
 # 3. Compiler-dependent part
 
@@ -70,6 +70,7 @@ test_mean_speed: mean_speed.o
 test_get_snapshot: ${obj_test_get_snapshot}
 test_set_all_outerm: ${obj_test_set_all_outerm}
 test_weight: ${obj_test_weight}
+test_spherical_polyline_area: spherical_polyline_area.o
 
 depend ${makefile_dir}/depend.mk:
 	makedepf90 -free -Wmissing -Wconfused $(addprefix -I, ${VPATH}) -nosrc $(addprefix -u , ${lib_list} shapelib netcdf intrinsic) ${sources} >${makefile_dir}/depend.mk
diff --git a/Tests/test_spherical_polyline_area.f b/Tests/test_spherical_polyline_area.f
new file mode 100644
index 0000000000000000000000000000000000000000..b77e28eb36fa8776e0ff5515adb10e185b49537c
--- /dev/null
+++ b/Tests/test_spherical_polyline_area.f
@@ -0,0 +1,22 @@
+program test_spherical_polyline_area
+
+  use contour_531, only: polyline
+  use nr_util, only: pi
+  use spherical_polyline_area_m, only: spherical_polyline_area
+
+  implicit none
+
+  real points(2, 4)
+  real, parameter:: deg2rad = pi / 180.
+
+  !-------------------------------------------------------------------------
+
+  points(:, 1) = [0., 0.]
+  points(:, 2) = [30. * deg2rad, 0.]
+  points(:, 3) = [0., 30. * deg2rad]
+  points(:, 4) = points(:, 1)
+  
+  print *, "Area = ", spherical_polyline_area(polyline(n_points = 4, &
+       closed = .true., points = points)) / 1e6, "km2"
+  
+end program test_spherical_polyline_area
diff --git a/Tests/tests.json b/Tests/tests.json
index 84ac3d1a6a275b8ab3ea14c16cfba71c6f735cf4..8de24f86895d43e63d6163069aba0718d284d75f 100644
--- a/Tests/tests.json
+++ b/Tests/tests.json
@@ -187,5 +187,9 @@
 	"input": "1e-3\n",
 	"description": "Same as Get_snapshot_region_4 with larger domain."
     },
-    {"args": "$compil_prod_dir/test_weight", "title": "Weight"}
+    {"args": "$compil_prod_dir/test_weight", "title": "Weight"},
+    {
+	"args": "$compil_prod_dir/test_spherical_polyline_area",
+	"title": "Spherical_polyline_area"
+    }
 ]
diff --git a/depend.mk b/depend.mk
index f0d4f7268e3a3a0518ab9b26baea2247f661afff..54428c2a0b807f71e73f0f6ec0668a6072a27295 100644
--- a/depend.mk
+++ b/depend.mk
@@ -17,3 +17,4 @@ test_good_contour.o : good_contour.o
 test_inside_4.o : inside_4.o 
 test_max_speed_contour_ssh.o : max_speed_contour_ssh.o 
 test_mean_speed.o : mean_speed.o 
+test_spherical_polyline_area.o : spherical_polyline_area.o 
diff --git a/spherical_polyline_area.f b/spherical_polyline_area.f
index 1c05d6ddc931d6622c0484725c3c5edd1b9d491f..59b96370dd6d9142a011ee1b97074017a4678b0c 100644
--- a/spherical_polyline_area.f
+++ b/spherical_polyline_area.f
@@ -6,8 +6,8 @@ contains
 
   pure real function spherical_polyline_area(p)
 
-    ! Assuming p is a polyline in longitude, latitude, in
-    ! rad. Computing the area of a polyline in longitude, sin(latitude)
+    ! Assuming p is a polyline in longitude, latitude, in rad, compute
+    ! the area (positive) of a polyline in longitude, sin(latitude)
     ! with the same vertices. Result in m2.
 
     use contour_531, only: polyline