diff --git a/sao/src/view/form.js b/sao/src/view/form.js
index 878d06aead..a85e0bac8c 100644
--- a/sao/src/view/form.js
+++ b/sao/src/view/form.js
@@ -5133,7 +5133,7 @@ function eval_pyson(value){
             this.input.prop('disabled', readonly);
         },
         set_value: function(value) {
-            this.input.prop('checked', value);
+            this.input.prop('checked', Boolean(value));
         }
     });
 
@@ -5236,7 +5236,8 @@ function eval_pyson(value){
             return value;
         },
         set_value: function(value, options) {
-            if (value !== null) {
+            if ((typeof(value) == 'number') ||
+                (value instanceof Sao.Decimal)) {
                 this.input.val(value);
                 this.input_text.val(value.toLocaleString(
                     Sao.i18n.BC47(Sao.i18n.getlang()), options));
@@ -5369,7 +5370,13 @@ function eval_pyson(value){
             return this._parse(this.format, this.input.val());
         },
         set_value: function(value) {
-            this.input.val(this._format(this.format, value));
+            if ((value instanceof Sao.DateTime) ||
+                (value instanceof Sao.Date)) {
+                value = this._format(this.format, value);
+            } else {
+                value = '';
+            }
+            this.input.val(value);
         },
     });
 
diff --git a/tryton/tryton/gui/window/view_form/view/form_gtk/dictionary.py b/tryton/tryton/gui/window/view_form/view/form_gtk/dictionary.py
index aff70f9f6e..25187cb1a2 100644
--- a/tryton/tryton/gui/window/view_form/view/form_gtk/dictionary.py
+++ b/tryton/tryton/gui/window/view_form/view/form_gtk/dictionary.py
@@ -1,6 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of this
 # repository contains the full copyright notices and license terms.
 
+import datetime as dt
 import decimal
 import gettext
 import locale
@@ -64,7 +65,7 @@ class DictEntry(object):
         return self.widget.get_text()
 
     def set_value(self, value):
-        self.widget.set_text(value or '')
+        self.widget.set_text(str(value or ''))
         reset_position(self.widget)
 
     def set_readonly(self, readonly):
@@ -279,7 +280,7 @@ class DictIntegerEntry(DictEntry):
         return None
 
     def set_value(self, value):
-        if value is not None:
+        if isinstance(value, (int, float, Decimal)):
             txt_val = locale.format_string('%d', value, True)
         else:
             txt_val = ''
@@ -316,7 +317,7 @@ class DictFloatEntry(DictIntegerEntry):
         else:
             self.widget.digits = None
         self.widget.set_width_chars(self.width)
-        if value is not None:
+        if isinstance(value, (int, float, Decimal)):
             txt_val = locale.localize(
                 '{0:.{1}f}'.format(value, digits[1]), True)
         else:
@@ -362,7 +363,8 @@ class DictDateTimeEntry(DictEntry):
         return untimezoned_date(self.widget.props.value)
 
     def set_value(self, value):
-        self.widget.props.value = timezoned_date(value)
+        self.widget.props.value = (
+            timezoned_date(value) if isinstance(value, dt.datetime) else None)
 
     def set_readonly(self, readonly):
         for child in self.widget.get_children():
@@ -397,7 +399,7 @@ class DictDateEntry(DictEntry):
         return self.widget.props.value
 
     def set_value(self, value):
-        self.widget.props.value = value
+        self.widget.props.value = value if isinstance(value, dt.date) else None
 
     def set_readonly(self, readonly):
         super().set_readonly(readonly)