Closes #149

src/main/scala/com/fasterxml/jackson/module/scala/DefaultScalaModule.scala

@@ -1,6 +1,6 @@
 package com.fasterxml.jackson.module.scala
 
-import com.fasterxml.jackson.module.scala.deser.{ScalaStdValueInstantiatorsModule, UntypedObjectDeserializerModule}
+import com.fasterxml.jackson.module.scala.deser.{ScalaNumberDeserializersModule, UntypedObjectDeserializerModule}
 import com.fasterxml.jackson.module.scala.introspect.ScalaAnnotationIntrospectorModule
 import com.fasterxml.jackson.module.scala.modifiers.EitherModule
 
@@ -26,7 +26,7 @@ class DefaultScalaModule
      with TupleModule
      with MapModule
      with SetModule
-     with ScalaStdValueInstantiatorsModule
+     with ScalaNumberDeserializersModule
      with ScalaAnnotationIntrospectorModule
      with UntypedObjectDeserializerModule
      with EitherModule

src/main/scala/com/fasterxml/jackson/module/scala/deser/ScalaNumberDeserializersModule.scala

@@ -0,0 +1,62 @@
+package com.fasterxml.jackson
+package module.scala
+package deser
+
+import com.fasterxml.jackson.core.JsonToken.{START_ARRAY, VALUE_NUMBER_FLOAT, VALUE_NUMBER_INT, VALUE_STRING}
+import com.fasterxml.jackson.core.{JsonParser, JsonToken}
+import com.fasterxml.jackson.databind.{JsonDeserializer, BeanDescription, DeserializationConfig, JavaType, DeserializationContext}
+import com.fasterxml.jackson.databind.DeserializationFeature.UNWRAP_SINGLE_VALUE_ARRAYS
+import com.fasterxml.jackson.databind.deser.Deserializers
+import com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer
+
+import scala.reflect.ClassTag
+import scala.reflect.classTag
+
+private abstract class BigNumberDeserializer[T >: Null : ClassTag](creator: (String) => T)
+  extends StdScalarDeserializer[T](classTag[T].runtimeClass)
+{
+  override def deserialize(jp: JsonParser, ctxt: DeserializationContext): T = {
+    val t = jp.getCurrentToken
+    t match {
+      case VALUE_NUMBER_INT | VALUE_NUMBER_FLOAT => creator(jp.getText.trim)
+      case VALUE_STRING =>
+        val text = jp.getText.trim
+        if (text.isEmpty) null else try {
+          creator(text)
+        }
+        catch {
+          case e: IllegalArgumentException => throw ctxt.weirdStringException(text, _valueClass, "not a valid representation")
+        }
+      case START_ARRAY if ctxt.isEnabled(UNWRAP_SINGLE_VALUE_ARRAYS) =>
+        jp.nextToken()
+        val value = deserialize(jp, ctxt)
+        if (jp.nextToken() != JsonToken.END_ARRAY) {
+          throw ctxt.wrongTokenException(jp, JsonToken.END_ARRAY, "Attempted to unwrap array for single value but there was more than a single value in the array")
+        }
+        value
+      case _ =>
+        throw ctxt.mappingException(_valueClass, t)
+    }
+  }
+}
+
+private object BigDecimalDeserializer extends BigNumberDeserializer(BigDecimal.apply)
+
+private object BigIntDeserializer extends BigNumberDeserializer(BigInt.apply)
+
+private object NumberDeserializers extends Deserializers.Base
+{
+  val BigDecimalClass = BigDecimalDeserializer.handledType()
+  val BigIntClass = BigIntDeserializer.handledType()
+
+  override def findBeanDeserializer(tpe: JavaType, config: DeserializationConfig, beanDesc: BeanDescription): JsonDeserializer[_] =
+    tpe.getRawClass match {
+      case BigDecimalClass => BigDecimalDeserializer
+      case BigIntClass => BigIntDeserializer
+      case _ => null
+    }
+}
+
+private [scala] trait ScalaNumberDeserializersModule extends JacksonModule {
+  this += NumberDeserializers
+}