diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb
index 26c5d3d78f34c7f7b722e24cdfb8283ee28d587c..78ef94b912436a50e9d3e69474041debc3fc5485 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/float.rb
@@ -7,6 +7,7 @@ class Float < Type::Float # :nodoc:
 
           def cast_value(value)
             case value
+            when ::Float then     value
             when 'Infinity' then  ::Float::INFINITY
             when '-Infinity' then -::Float::INFINITY
             when 'NaN' then       ::Float::NAN
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index 7f09b01713f8706ae39d2ac0ff2c36e7452254de..7c485eb9d0f40399be28cfedd877d39fb8390b0d 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -29,9 +29,7 @@ def quote(value, column = nil) #:nodoc:
               super
             end
           when Float
-            if value.infinite? && column.type == :datetime
-              "'#{value.to_s.downcase}'"
-            elsif value.infinite? || value.nan?
+            if value.infinite? || value.nan?
               "'#{value.to_s}'"
             else
               super
diff --git a/activerecord/test/cases/adapters/postgresql/infinity_test.rb b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
new file mode 100644
index 0000000000000000000000000000000000000000..22e8873333377c5b25a61b041745fdc629954811
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
@@ -0,0 +1,44 @@
+require "cases/helper"
+
+class PostgresqlInfinityTest < ActiveRecord::TestCase
+  class PostgresqlInfinity < ActiveRecord::Base
+  end
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table(:postgresql_infinities) do |t|
+      t.float :float
+      t.datetime :datetime
+    end
+  end
+
+  teardown do
+    @connection.execute("DROP TABLE IF EXISTS postgresql_infinities")
+  end
+
+  test "type casting infinity on a float column" do
+    record = PostgresqlInfinity.create!(float: Float::INFINITY)
+    record.reload
+    assert_equal Float::INFINITY, record.float
+  end
+
+  test "update_all with infinity on a float column" do
+    record = PostgresqlInfinity.create!
+    PostgresqlInfinity.update_all(float: Float::INFINITY)
+    record.reload
+    assert_equal Float::INFINITY, record.float
+  end
+
+  test "type casting infinity on a datetime column" do
+    record = PostgresqlInfinity.create!(datetime: Float::INFINITY)
+    record.reload
+    assert_equal Float::INFINITY, record.datetime
+  end
+
+  test "update_all with infinity on a datetime column" do
+    record = PostgresqlInfinity.create!
+    PostgresqlInfinity.update_all(datetime: Float::INFINITY)
+    record.reload
+    assert_equal Float::INFINITY, record.datetime
+  end
+end