diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index 4d9186017ffbd96c71cfc1fa952bc9fd923d7d23..890e99415f57e05a43505028a5e7595922f78f0c 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Allow proc and symbol as values for `only_integer` of `NumericalityValidator`
+
+    *Robin Mehner*
+
 *   `has_secure_password` now verifies that the given password is less than 72
     characters if validations are enabled.
 
diff --git a/activemodel/lib/active_model/validations/numericality.rb b/activemodel/lib/active_model/validations/numericality.rb
index a9fb9804d43f4c92027137ff1581f72157032456..5bd162433dcaf11dbf46df82c3b8e97c4d22a3a8 100644
--- a/activemodel/lib/active_model/validations/numericality.rb
+++ b/activemodel/lib/active_model/validations/numericality.rb
@@ -30,7 +30,7 @@ def validate_each(record, attr_name, value)
           return
         end
 
-        if options[:only_integer]
+        if allow_only_integer?(record)
           unless value = parse_raw_value_as_an_integer(raw_value)
             record.errors.add(attr_name, :not_an_integer, filtered_options(raw_value))
             return
@@ -75,6 +75,17 @@ def filtered_options(value)
         filtered[:value] = value
         filtered
       end
+
+      def allow_only_integer?(record)
+        case options[:only_integer]
+        when Symbol
+          record.send(options[:only_integer])
+        when Proc
+          options[:only_integer].call(record)
+        else
+          options[:only_integer]
+        end
+      end
     end
 
     module HelperMethods
@@ -121,6 +132,7 @@ module HelperMethods
       # * <tt>:equal_to</tt>
       # * <tt>:less_than</tt>
       # * <tt>:less_than_or_equal_to</tt>
+      # * <tt>:only_integer</tt>
       #
       # For example:
       #
diff --git a/activemodel/test/cases/validations/numericality_validation_test.rb b/activemodel/test/cases/validations/numericality_validation_test.rb
index e1657407cf0605d69baa883cd258fd5716d28733..3834d327eafb535cc0beeedce6f2218b7fe7c3eb 100644
--- a/activemodel/test/cases/validations/numericality_validation_test.rb
+++ b/activemodel/test/cases/validations/numericality_validation_test.rb
@@ -50,6 +50,21 @@ def test_validates_numericality_of_with_integer_only_and_nil_allowed
     valid!(NIL + INTEGERS)
   end
 
+  def test_validates_numericality_of_with_integer_only_and_symbol_as_value
+    Topic.validates_numericality_of :approved, only_integer: :condition_is_true_but_its_not
+
+    invalid!(NIL + BLANK + JUNK)
+    valid!(FLOATS + INTEGERS + BIGDECIMAL + INFINITY)
+  end
+
+  def test_validates_numericality_of_with_integer_only_and_proc_as_value
+    Topic.send(:define_method, :allow_only_integers?, lambda { false })
+    Topic.validates_numericality_of :approved, only_integer: Proc.new {|topic| topic.allow_only_integers? }
+
+    invalid!(NIL + BLANK + JUNK)
+    valid!(FLOATS + INTEGERS + BIGDECIMAL + INFINITY)
+  end
+
   def test_validates_numericality_with_greater_than
     Topic.validates_numericality_of :approved, greater_than: 10