diff --git a/activemodel/lib/active_model/type/decimal.rb b/activemodel/lib/active_model/type/decimal.rb
index 541a12c8a1..b4ba8d4b1f 100644
--- a/activemodel/lib/active_model/type/decimal.rb
+++ b/activemodel/lib/active_model/type/decimal.rb
@@ -21,8 +21,10 @@ module ActiveModel
             case value
             when ::Float
               convert_float_to_big_decimal(value)
-            when ::Numeric, ::String
+            when ::Numeric
               BigDecimal(value, precision || BIGDECIMAL_PRECISION)
+            when ::String
+              value.to_d rescue BigDecimal(0)
             else
               if value.respond_to?(:to_d)
                 value.to_d
diff --git a/activemodel/test/cases/type/decimal_test.rb b/activemodel/test/cases/type/decimal_test.rb
index 46a913258e..c3b43725cc 100644
--- a/activemodel/test/cases/type/decimal_test.rb
+++ b/activemodel/test/cases/type/decimal_test.rb
@@ -11,6 +11,14 @@ module ActiveModel
         assert_equal BigDecimal.new("1"), type.cast(:"1")
       end
 
+      def test_type_cast_decimal_from_invalid_string
+        type = Decimal.new
+        assert_nil type.cast("")
+        assert_equal BigDecimal.new("1"), type.cast("1ignore")
+        assert_equal BigDecimal.new("0"), type.cast("bad1")
+        assert_equal BigDecimal.new("0"), type.cast("bad")
+      end
+
       def test_type_cast_decimal_from_float_with_large_precision
         type = Decimal.new(precision: ::Float::DIG + 2)
         assert_equal BigDecimal.new("123.0"), type.cast(123.0)
diff --git a/activemodel/test/cases/type/float_test.rb b/activemodel/test/cases/type/float_test.rb
index 2e34f57f7e..8026d63ad5 100644
--- a/activemodel/test/cases/type/float_test.rb
+++ b/activemodel/test/cases/type/float_test.rb
@@ -9,6 +9,14 @@ module ActiveModel
         assert_equal 1.0, type.cast("1")
       end
 
+      def test_type_cast_float_from_invalid_string
+        type = Type::Float.new
+        assert_nil type.cast("")
+        assert_equal 1.0, type.cast("1ignore")
+        assert_equal 0.0, type.cast("bad1")
+        assert_equal 0.0, type.cast("bad")
+      end
+
       def test_changing_float
         type = Type::Float.new
 
diff --git a/activemodel/test/cases/type/integer_test.rb b/activemodel/test/cases/type/integer_test.rb
index 2b9b03f3cf..a91144036b 100644
--- a/activemodel/test/cases/type/integer_test.rb
+++ b/activemodel/test/cases/type/integer_test.rb
@@ -7,6 +7,7 @@ module ActiveModel
     class IntegerTest < ActiveModel::TestCase
       test "simple values" do
         type = Type::Integer.new
+        assert_nil type.cast("")
         assert_equal 1, type.cast(1)
         assert_equal 1, type.cast("1")
         assert_equal 1, type.cast("1ignore")