diff --git a/sorc/orog_mask_tools.fd/orog.fd/io_utils.F90 b/sorc/orog_mask_tools.fd/orog.fd/io_utils.F90
index a89d6e238..d6dc508cc 100644
--- a/sorc/orog_mask_tools.fd/orog.fd/io_utils.F90
+++ b/sorc/orog_mask_tools.fd/orog.fd/io_utils.F90
@@ -343,9 +343,9 @@ end subroutine write_mask_netcdf
 !> Read the land mask file
 !!
 !! @param[in] merge_file path 
-!! @param[in] slm Land-sea mask.
-!! @param[in] land_frac Land fraction.
-!! @param[in] lake_frac Lake fraction
+!! @param[out] slm Land-sea mask.
+!! @param[out] land_frac Land fraction.
+!! @param[out] lake_frac Lake fraction
 !! @param[in] im 'i' dimension of a model grid tile.
 !! @param[in] jm 'j' dimension of a model grid tile.
 !! @author George Gayno NOAA/EMC
diff --git a/tests/orog/CMakeLists.txt b/tests/orog/CMakeLists.txt
index 7986143ea..ca02d8215 100644
--- a/tests/orog/CMakeLists.txt
+++ b/tests/orog/CMakeLists.txt
@@ -23,6 +23,10 @@ execute_process( COMMAND ${CMAKE_COMMAND} -E copy
 execute_process( COMMAND ${CMAKE_COMMAND} -E copy
     ${CMAKE_CURRENT_SOURCE_DIR}/data/C12_grid.tile1.nc ${CMAKE_CURRENT_BINARY_DIR}/C12_grid.tile1.nc)
 
+# Note, the "read_mask" test expects this file.
+execute_process( COMMAND ${CMAKE_COMMAND} -E copy
+    ${CMAKE_CURRENT_SOURCE_DIR}/data/C48.mx500.tile1.nc ${CMAKE_CURRENT_BINARY_DIR}/C48.mx500.tile1.nc)
+
 add_executable(ftst_ll2xyz ftst_ll2xyz.F90)
 add_test(NAME orog-ftst_ll2xyz COMMAND ftst_ll2xyz)
 target_link_libraries(ftst_ll2xyz orog_lib)
@@ -86,3 +90,7 @@ target_link_libraries(ftst_read_mdl_dims orog_lib)
 add_executable(ftst_read_mdl_grid_file ftst_read_mdl_grid_file.F90)
 add_test(NAME orog-ftst_read_mdl_grid_file COMMAND ftst_read_mdl_grid_file)
 target_link_libraries(ftst_read_mdl_grid_file orog_lib)
+
+add_executable(ftst_read_mask ftst_read_mask.F90)
+add_test(NAME orog-ftst_read_mask COMMAND ftst_read_mask)
+target_link_libraries(ftst_read_mask orog_lib)
diff --git a/tests/orog/data/C48.mx500.tile1.nc b/tests/orog/data/C48.mx500.tile1.nc
new file mode 100644
index 000000000..51b5fc0a4
Binary files /dev/null and b/tests/orog/data/C48.mx500.tile1.nc differ
diff --git a/tests/orog/ftst_read_mask.F90 b/tests/orog/ftst_read_mask.F90
new file mode 100644
index 000000000..e7d9f552f
--- /dev/null
+++ b/tests/orog/ftst_read_mask.F90
@@ -0,0 +1,82 @@
+ program read_mask_test
+
+! Test routine 'read_mask' by reading a sample C48 global
+! uniform tile file.
+!
+! Author George Gayno NCEP/EMC
+
+ use io_utils, only      : read_mask
+
+ implicit none
+
+ character(len=20)       :: merge_file
+
+ integer, parameter      :: im=48
+ integer, parameter      :: jm=48
+ integer, parameter      :: chk_pts = 4
+ integer                 :: i, j, ij
+
+ real, parameter         :: EPSILON = 0.001
+ real                    :: land_frac(im,jm)
+ real                    :: lake_frac(im,jm)
+ real                    :: slm(im,jm)
+ real                    :: land_frac_chk(chk_pts)
+ real                    :: lake_frac_chk(chk_pts)
+ real                    :: slm_chk(chk_pts)
+
+ type :: indices
+  integer :: i
+  integer :: j
+ end type indices
+
+ type(indices)           :: idx(chk_pts)
+
+! The i/j indicies of the check points.
+
+ data idx%i /1,29,47,48/
+ data idx%j /1,25,23,48/
+
+! The expected values of the check points.
+
+ data land_frac_chk /0.58463, 0.8377, 0.0, 0.415374/
+ data lake_frac_chk /0.0, 0.0, 1.0, 0.0/
+ data slm_chk /1.0, 1.0, 0.0, 0.0/
+
+ print*,"- Starting test of routine read_mask."
+
+ merge_file = "./C48.mx500.tile1.nc"
+
+! Initialize output fields to flag value.
+
+ land_frac = -999.9
+ lake_frac = -999.9
+ slm       = -999.9
+
+ call read_mask(merge_file,slm,land_frac,lake_frac,im,jm)
+
+! All flag values should have been replaced. All fields
+! should have values greater than zero.
+
+ do j = 1, jm
+ do i = 1, im
+   if (land_frac(i,j) < 0.0) stop 3
+   if (lake_frac(i,j) < 0.0) stop 5
+   if (slm(i,j) < 0.0) stop 7
+ enddo
+ enddo
+ 
+! Check some points against expected values.
+
+ do ij = 1, chk_pts
+   i = idx(ij)%i
+   j = idx(ij)%j
+   if (abs(land_frac(i,j)-land_frac_chk(ij)) > EPSILON) stop 12
+   if (abs(lake_frac(i,j)-lake_frac_chk(ij)) > EPSILON) stop 15
+   if (abs(slm(i,j)-slm_chk(ij)) > EPSILON) stop 18
+ enddo
+
+ print*,"OK"
+
+ print*,"SUCCESS"
+
+ end program read_mask_test