diff --git a/django/core/management/validation.py b/django/core/management/validation.py
index 554c59e856..f0a9056871 100644
--- a/django/core/management/validation.py
+++ b/django/core/management/validation.py
@@ -37,13 +37,26 @@ def get_validation_errors(outfile, app=None):
                 e.add(opts, '"%s": You can\'t use "id" as a field name, because each model automatically gets an "id" field if none of the fields have primary_key=True. You need to either remove/rename your "id" field or add primary_key=True to a field.' % f.name)
             if f.name.endswith('_'):
                 e.add(opts, '"%s": Field names cannot end with underscores, because this would lead to ambiguous queryset filters.' % f.name)
-            if isinstance(f, models.CharField) and f.max_length in (None, 0):
-                e.add(opts, '"%s": CharFields require a "max_length" attribute.' % f.name)
+            if isinstance(f, models.CharField):
+                try:
+                    max_length = int(f.max_length)
+                    if max_length <= 0:
+                        e.add(opts, '"%s": CharFields require a "max_length" attribute that is a positive integer.' % f.name)
+                except (ValueError, TypeError):
+                    e.add(opts, '"%s": CharFields require a "max_length" attribute that is a positive integer.' % f.name)
             if isinstance(f, models.DecimalField):
-                if f.decimal_places is None:
-                    e.add(opts, '"%s": DecimalFields require a "decimal_places" attribute.' % f.name)
-                if f.max_digits is None:
-                    e.add(opts, '"%s": DecimalFields require a "max_digits" attribute.' % f.name)
+                try:
+                    decimal_places = int(f.decimal_places)
+                    if decimal_places <= 0:
+                        e.add(opts, '"%s": DecimalFields require a "decimal_places" attribute that is a positive integer.' % f.name)
+                except (ValueError, TypeError):
+                    e.add(opts, '"%s": DecimalFields require a "decimal_places" attribute that is a positive integer.' % f.name)
+                try:
+                    max_digits = int(f.max_digits)
+                    if max_digits <= 0:
+                        e.add(opts, '"%s": DecimalFields require a "max_digits" attribute that is a positive integer.' % f.name)
+                except (ValueError, TypeError):
+                    e.add(opts, '"%s": DecimalFields require a "max_digits" attribute that is a positive integer.' % f.name)
             if isinstance(f, models.FileField) and not f.upload_to:
                 e.add(opts, '"%s": FileFields require an "upload_to" attribute.' % f.name)
             if isinstance(f, models.ImageField):
diff --git a/tests/modeltests/invalid_models/models.py b/tests/modeltests/invalid_models/models.py
index 8aa7678930..26c393be96 100644
--- a/tests/modeltests/invalid_models/models.py
+++ b/tests/modeltests/invalid_models/models.py
@@ -8,7 +8,11 @@ from django.db import models
 
 class FieldErrors(models.Model):
     charfield = models.CharField()
+    charfield2 = models.CharField(max_length=-1)
+    charfield3 = models.CharField(max_length="bad")
     decimalfield = models.DecimalField()
+    decimalfield2 = models.DecimalField(max_digits=-1, decimal_places=-1)
+    decimalfield3 = models.DecimalField(max_digits="bad", decimal_places="bad")
     filefield = models.FileField()
     choices = models.CharField(max_length=10, choices='bad')
     choices2 = models.CharField(max_length=10, choices=[(1,2,3),(1,2,3)])
@@ -203,9 +207,15 @@ class UniqueFKTarget2(models.Model):
     tgt = models.ForeignKey(FKTarget, to_field='good')
 
 
-model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute.
-invalid_models.fielderrors: "decimalfield": DecimalFields require a "decimal_places" attribute.
-invalid_models.fielderrors: "decimalfield": DecimalFields require a "max_digits" attribute.
+model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute that is a positive integer.
+invalid_models.fielderrors: "charfield2": CharFields require a "max_length" attribute that is a positive integer.
+invalid_models.fielderrors: "charfield3": CharFields require a "max_length" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield": DecimalFields require a "decimal_places" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield": DecimalFields require a "max_digits" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield2": DecimalFields require a "decimal_places" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield2": DecimalFields require a "max_digits" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield3": DecimalFields require a "decimal_places" attribute that is a positive integer.
+invalid_models.fielderrors: "decimalfield3": DecimalFields require a "max_digits" attribute that is a positive integer.
 invalid_models.fielderrors: "filefield": FileFields require an "upload_to" attribute.
 invalid_models.fielderrors: "choices": "choices" should be iterable (e.g., a tuple or list).
 invalid_models.fielderrors: "choices2": "choices" should be a sequence of two-tuples.