diff --git a/pdeutils/quadrature/simplexQuadratureRule.m b/pdeutils/quadrature/simplexQuadratureRule.m
index fbd6c57e6b27d287b9567f6c5edc41b3aae4a811..cad4c4e5042cdb766c25e92c8b6082d26400b583 100644
--- a/pdeutils/quadrature/simplexQuadratureRule.m
+++ b/pdeutils/quadrature/simplexQuadratureRule.m
@@ -27,6 +27,9 @@ function Q = simplexQuadratureRule(dim, order)
         weights = [A B B B C C C];
 
         order = 5;
+    else
+        error( 'The parameters (dim=%d, order=%d) are not supported.', ...
+                dim, order );
     end
 
     Q = struct('size', length(weights), 'points', points, 'weights', weights, 'order', order);