diff --git a/src/main/scala/org/change/v2/analysis/expression/concrete/ConstantValue.scala b/src/main/scala/org/change/v2/analysis/expression/concrete/ConstantValue.scala
index b9fae2b..14ecd4d 100755
--- a/src/main/scala/org/change/v2/analysis/expression/concrete/ConstantValue.scala
+++ b/src/main/scala/org/change/v2/analysis/expression/concrete/ConstantValue.scala
@@ -9,7 +9,7 @@ import z3.scala.{Z3Solver, Z3AST}
  * Created by radu on 3/24/15.
  */
 case class ConstantValue(value: Long) extends Expression with FloatingExpression {
-  lazy val ast = Z3Util.z3Context.mkInt(value.asInstanceOf[Int], Z3Util.defaultSort)
+  lazy val ast = Z3Util.z3Context.mkNumeral(value.toString, Z3Util.defaultSort)
 
   override def toZ3(solver: Option[Z3Solver] = None): (Z3AST, Option[Z3Solver]) = (ast, solver)
 
@@ -26,7 +26,7 @@ case class ConstantValue(value: Long) extends Expression with FloatingExpression
 }
 
 case class ConstantBitVector(value: Long) extends Expression with FloatingExpression {
-  lazy val ast = Z3Util.z3Context.mkInt(value.asInstanceOf[Int], Z3Util.bv32Sort)
+  lazy val ast = Z3Util.z3Context.mkNumeral(value.toString, Z3Util.bv32Sort)
 
   override def toZ3(solver: Option[Z3Solver] = None): (Z3AST, Option[Z3Solver]) = (ast, solver)
 
diff --git a/src/main/scala/org/change/v2/analysis/processingmodels/instructions/InstructionBlock.scala b/src/main/scala/org/change/v2/analysis/processingmodels/instructions/InstructionBlock.scala
index 1e5e086..7de6fd3 100755
--- a/src/main/scala/org/change/v2/analysis/processingmodels/instructions/InstructionBlock.scala
+++ b/src/main/scala/org/change/v2/analysis/processingmodels/instructions/InstructionBlock.scala
@@ -14,15 +14,19 @@ case class InstructionBlock(instructions: Iterable[Instruction]) extends Instruc
    * @param s
    * @return
    */
-  override def apply(s: State, v: Boolean): (List[State], List[State]) =
+  override def apply(s: State, v: Boolean): (List[State], List[State]) = {
+    val initialHistory = s.history
+
     instructions.foldLeft((List(s), Nil: List[State])) { (acc, i) => {
-        val (valid: List[State], failed: List[State]) = acc
-        val (nextValid, nextFailed) = valid.map(i(_, v)).unzip
-        val allValid = nextValid.foldLeft(Nil: List[State])(_ ++ _)
-        val allFailed = nextFailed.foldLeft(failed: List[State])(_ ++ _)
+        val (valid, failed) = acc
+        val (forwarded, notForwarded) = valid.partition(_.history != s.history)
+        val (nextValid, nextFailed) = notForwarded.map(i(_, v)).unzip
+        val allValid = nextValid.foldLeft(forwarded)(_ ++ _)
+        val allFailed = nextFailed.foldLeft(failed)(_ ++ _)
         (allValid, allFailed)
       }
     }
+  }
 }
 
 object InstructionBlock {