diff --git a/openerp/addons/base/ir/ir_fields.py b/openerp/addons/base/ir/ir_fields.py
index 621dd93d469..ba6681bee15 100644
--- a/openerp/addons/base/ir/ir_fields.py
+++ b/openerp/addons/base/ir/ir_fields.py
@@ -100,10 +100,20 @@ class ir_fields_converter(orm.Model):
         return True
 
     def _str_to_integer(self, cr, uid, model, column, value, context=None):
-        return int(value)
+        try:
+            return int(value)
+        except ValueError:
+            raise ValueError(
+                _(u"'%s' does not seem to be an integer for field '%%(field)s'")
+                % value)
 
     def _str_to_float(self, cr, uid, model, column, value, context=None):
-        return float(value)
+        try:
+            return float(value)
+        except ValueError:
+            raise ValueError(
+                _(u"'%s' does not seem to be a number for field '%%(field)s'")
+                % value)
 
     def _str_to_char(self, cr, uid, model, column, value, context=None):
         return value
diff --git a/openerp/tests/addons/test_impex/tests/test_load.py b/openerp/tests/addons/test_impex/tests/test_load.py
index 72442963af5..032dd65ef07 100644
--- a/openerp/tests/addons/test_impex/tests/test_load.py
+++ b/openerp/tests/addons/test_impex/tests/test_load.py
@@ -275,7 +275,7 @@ class test_integer_field(ImporterCase):
             'rows': {'from': 0, 'to': 0},
             'record': 0,
             'field': 'value',
-            'message': u"invalid literal for int() with base 10: 'zorglub'",
+            'message': u"'zorglub' does not seem to be an integer for field 'unknown'",
         }])
 
 class test_float_field(ImporterCase):
@@ -344,7 +344,7 @@ class test_float_field(ImporterCase):
             'rows': {'from': 0, 'to': 0},
             'record': 0,
             'field': 'value',
-            'message': u"invalid literal for float(): foobar",
+            'message': u"'foobar' does not seem to be a number for field 'unknown'",
         }])
 
 class test_string_field(ImporterCase):