diff --git a/polymani.pl b/polymani.pl
index f26c59e..f6950fc 100644
--- a/polymani.pl
+++ b/polymani.pl
@@ -313,6 +313,12 @@ print_all_stored_variables([]).
 %
 %  Flatten a polynomail tree into a simple polynomial
 %
+polynomial_tree_to_polynomial(op(neg, T), P1) :-
+    %% If it matched on the version with a node, don't go back
+    !,
+    %% Delegate
+    polynomial_tree_to_polynomial(T, P),
+    atom_concat('-', P, P1).
 polynomial_tree_to_polynomial(op(Op, TL, TR), P) :-
     %% If it matched on the version with a node, don't go back
     !,
@@ -473,6 +479,7 @@ parse_floating_number(TN) -->
 %@ TN = op('.', 2, 4).
 %% ?- parse_floating_number(TN, [negative, two, dot, 4], _).
 %@ TN = op('.', op(neg, 2), 4).
+%@ TN = op('.', op(neg, 2), 4).
 
 %% parse_positive_integer_number(-tree, +stream, -not_consumed) is det
 %
@@ -498,7 +505,7 @@ parse_integer_number(N) -->
 parse_integer_number(op(neg, T)) -->    % TODO
     %% A number can start with "negative", to negate it
     [negative],
-    parse_number_explicit(void, void, T).
+    parse_integer_number(T).
 parse_integer_number(T) -->
     parse_number_explicit(void, void, T).
 %% Tests: