diff --git a/django/core/validators.py b/django/core/validators.py
index 874edaefdd..e728dbc0ed 100644
--- a/django/core/validators.py
+++ b/django/core/validators.py
@@ -18,7 +18,7 @@ except ImportError:
 from django.conf import settings
 from django.utils.translation import ugettext as _, ugettext_lazy, ungettext
 from django.utils.functional import Promise, lazy
-from django.utils.encoding import force_unicode
+from django.utils.encoding import force_unicode, smart_str
 
 _datere = r'\d{4}-\d{1,2}-\d{1,2}'
 _timere = r'(?:[01]?[0-9]|2[0-3]):[0-5][0-9](?::[0-5][0-9])?'
@@ -451,7 +451,7 @@ class IsValidDecimal(object):
                 "Please enter a valid decimal number with at most %s decimal places.", self.decimal_places) % self.decimal_places
 
 def isValidFloat(field_data, all_data):
-    data = str(field_data)
+    data = smart_str(field_data)
     try:
         float(data)
     except ValueError:
diff --git a/tests/modeltests/manipulators/models.py b/tests/modeltests/manipulators/models.py
index 2ee81f62b3..c9b9848235 100644
--- a/tests/modeltests/manipulators/models.py
+++ b/tests/modeltests/manipulators/models.py
@@ -1,3 +1,4 @@
+# coding: utf-8
 """
 27. Default manipulators
 
@@ -21,7 +22,7 @@ class Album(models.Model):
     def __unicode__(self):
         return self.name
 
-__test__ = {'API_TESTS':"""
+__test__ = {'API_TESTS':u"""
 >>> from django.utils.datastructures import MultiValueDict
 
 # Create a Musician object via the default AddManipulator.
@@ -88,4 +89,9 @@ True
 <Album: Ultimate Ella>
 >>> a2.release_date
 datetime.date(2005, 2, 13)
+
+# Test isValidFloat Unicode coercion
+>>> from django.core.validators import isValidFloat, ValidationError
+>>> try: isValidFloat(u"ä", None)
+... except ValidationError: pass
 """}