diff --git a/src/gray_errors.f90 b/src/gray_errors.f90
index 8c1f2a8..0aa795b 100644
--- a/src/gray_errors.f90
+++ b/src/gray_errors.f90
@@ -142,8 +142,11 @@ contains
     integer,                  intent(in), optional :: subcase
     integer(kind=gray_error)             :: raise_error
 
-    raise_error = ibset(error, spec%offset &
-                               + merge(subcase, 0, present(subcase)))
+    if (present(subcase)) then
+      raise_error = ibset(error, spec%offset + subcase)
+    else
+      raise_error = ibset(error, spec%offset)
+    end if
   end function raise_error