diff --git a/trytond/ir/ui/graph.dtd b/trytond/ir/ui/graph.dtd
index 017fe8fef8..396512c75d 100644
--- a/trytond/ir/ui/graph.dtd
+++ b/trytond/ir/ui/graph.dtd
@@ -14,6 +14,7 @@
 <!ATTLIST field fill (0|1) #IMPLIED>
 <!ATTLIST field empty (0|1) #IMPLIED>
 <!ATTLIST field color CDATA #IMPLIED>
+<!ATTLIST field widget (float_time) #IMPLIED>
 <!ELEMENT data (xpath+)>
 <!ELEMENT xpath ANY>
 <!ATTLIST xpath expr CDATA #REQUIRED>