diff --git a/spray-json/jvm/src/test/scala/spray/json/JsonParserSpecJvm.scala b/spray-json/jvm/src/test/scala/spray/json/JsonParserSpecJvm.scala
index df83670..32097bc 100644
--- a/spray-json/jvm/src/test/scala/spray/json/JsonParserSpecJvm.scala
+++ b/spray-json/jvm/src/test/scala/spray/json/JsonParserSpecJvm.scala
@@ -60,7 +60,9 @@ class JsonParserSpecJvm extends Specification {
         queue.peek
       }
 
-      val i: Int = Iterator.iterate(1)(1.+).indexWhere(depth => probe(depth, maxDepth = 1000) contains "stackoverflow")
+      // Explicit type needed to compile on Scala 2.10, can be inlined later
+      def inc(i: Int): Int = 1 + i
+      val i: Int = Iterator.iterate(1)(inc).indexWhere(depth => probe(depth, maxDepth = 1000) contains "stackoverflow")
       println(s"Overflowing stack at $i which means we need about ${stackSize / i} bytes per recursive call")
 
       val maxDepth = i / 4 // should give lots of room