diff --git a/pfio/FileMetadata.F90 b/pfio/FileMetadata.F90
index 73e33927885d..2d3cae3c5590 100644
--- a/pfio/FileMetadata.F90
+++ b/pfio/FileMetadata.F90
@@ -123,11 +123,20 @@ subroutine add_dimension(this, dim_name, extent, unusable, rc)
       class (FileMetadata), target, intent(inout) :: this
       character(len=*), intent(in) :: dim_name
       integer, intent(in) :: extent
-
       class (KeywordEnforcer), optional, intent(in) :: unusable
       integer, optional, intent(out) :: rc
 
-      call this%dimensions%insert(dim_name, extent)
+      integer :: existing_extent
+
+      if (.not. this%has_dimension(dim_name)) then
+         call this%dimensions%insert(dim_name, extent)
+         _RETURN(_SUCCESS)
+      end if
+
+      ! Otherwise verify consistency
+      existing_extent = this%get_dimension(dim_name)
+      _ASSERT(extent == existing_extent,'FileMetadata::add_dimension() - dimension already exists with different extent.')
+
       _RETURN(_SUCCESS)
       _UNUSED_DUMMY(unusable)
    end subroutine add_dimension
diff --git a/pfio/tests/Test_FileMetadata.pf b/pfio/tests/Test_FileMetadata.pf
index 4b324c8d8850..284f4683bcb5 100644
--- a/pfio/tests/Test_FileMetadata.pf
+++ b/pfio/tests/Test_FileMetadata.pf
@@ -49,6 +49,26 @@ contains
       
    end subroutine test_get_dimension
 
+   @test
+   subroutine test_fail_add_existing_dim_with_mismatch()
+      type (FileMetadata) :: cf
+
+      call cf%add_dimension('x', 10)
+      call cf%add_dimension('x', 11)
+
+      @assertExceptionRaised('FileMetadata::add_dimension() - dimension already exists with different extent.')
+
+   end subroutine test_fail_add_existing_dim_with_mismatch
+
+   @test
+   subroutine test_add_duplicate_dimension()
+      type (FileMetadata) :: cf
+
+      call cf%add_dimension('x', 10)
+      call cf%add_dimension('x', 10)
+
+   end subroutine test_add_duplicate_dimension
+
    @test
    subroutine test_get_dimensions()
       type (FileMetadata), target :: cf