diff --git a/src/main/scala/apps/gemv.scala b/src/main/scala/apps/gemv.scala
index cd22cb5da..bdf48916c 100644
--- a/src/main/scala/apps/gemv.scala
+++ b/src/main/scala/apps/gemv.scala
@@ -84,7 +84,7 @@ object gemv {
           zip(xs)(t._1) |>
             split(n) |>
             toLocalFun(mapLocal(
-              reduceSeq(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
+              oclReduceSeq(AddressSpace.Private)(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
             )) |>
             mapLocal(fun(x => (alpha * x) + (t._2 * beta)))
         )) |> join
@@ -99,10 +99,10 @@ object gemv {
             reorderWithStride(128) |>
             split(n /^ 128) |>
             toLocalFun(mapLocal(
-              reduceSeq(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
+              oclReduceSeq(AddressSpace.Private)(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
             )) |>
             split(128) |>
-            toLocalFun(mapLocal(reduceSeq(add)(lf32(0.0f)))) |>
+            toLocalFun(mapLocal(oclReduceSeq(AddressSpace.Private)(add)(lf32(0.0f)))) |>
             mapLocal(fun(x => (alpha * x) + (t._2 * beta)))
         )) |> join
     ))
@@ -117,9 +117,9 @@ object gemv {
             reorderWithStride(128) |>
             split(n /^ 128) |>
             toLocalFun(mapLocal(
-              reduceSeq(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
+              oclReduceSeq(AddressSpace.Private)(fun(a => fun(x => mult(x) + a)))(lf32(0.0f))
             )) |>
-            toLocalFun(reduceSeq(add)(lf32(0.0f))) |>
+            toLocalFun(oclReduceSeq(AddressSpace.Private)(add)(lf32(0.0f))) |>
             fun(x => (alpha * x) + (t._2 * beta))
         ))
     ))
diff --git a/src/main/scala/shine/OpenCL/Compilation/SeparateHostAndKernelCode.scala b/src/main/scala/shine/OpenCL/Compilation/SeparateHostAndKernelCode.scala
index 35c267985..5afc81018 100644
--- a/src/main/scala/shine/OpenCL/Compilation/SeparateHostAndKernelCode.scala
+++ b/src/main/scala/shine/OpenCL/Compilation/SeparateHostAndKernelCode.scala
@@ -1,7 +1,7 @@
 package shine.OpenCL.Compilation
 
 import arithexpr.arithmetic.NamedVar
-import rise.core.types.{DataKind, DataType, NatIdentifier, NatKind}
+import rise.core.types.{DataKind, DataType, NatIdentifier, NatKind, NatToNat, NatToNatLambda}
 import rise.core.types.DataType.DataTypeIdentifier
 import shine.DPIA.Compilation.FunDef
 import shine.DPIA.Phrases._
@@ -90,8 +90,8 @@ object SeparateHostAndKernelCode {
   // TODO: collect free nat identifiers?
   private def freeVariables(p: Phrase[_ <: PhraseType])
   : (Set[Identifier[ExpType]], Set[NamedVar]) = {
-    var idents = scala.collection.mutable.Set[Identifier[ExpType]]()
-    var natIdents = scala.collection.mutable.Set[NamedVar]()
+    val idents = scala.collection.mutable.Set[Identifier[ExpType]]()
+    val natIdents = scala.collection.mutable.Set[NamedVar]()
 
     case class Visitor(boundV: Set[Identifier[_]],
                        boundT: Set[DataTypeIdentifier],
@@ -110,6 +110,12 @@ object SeparateHostAndKernelCode {
         case _ => Continue(p, this)
       }
 
+      override def natToNat(ft: NatToNat): NatToNat = ft match {
+        case NatToNatLambda(x, b) =>
+          NatToNatLambda(x, this.copy(boundN = boundN + x).nat(b))
+        case _ => super.natToNat(ft)
+      }
+
       override def nat[N <: Nat](n: N): N = {
         natIdents ++= n.varList.collect {
           case v: NamedVar if !boundN(v) => v
diff --git a/src/test/scala/apps/gemvCheck.scala b/src/test/scala/apps/gemvCheck.scala
index 933ee86e4..db1b51562 100644
--- a/src/test/scala/apps/gemvCheck.scala
+++ b/src/test/scala/apps/gemvCheck.scala
@@ -3,10 +3,13 @@ package apps
 import gemv._
 import rise.core.DSL._
 import Type._
+import rise.autotune
+import rise.core.Expr
 import rise.core.types._
-import util.gen
+import util.{gen}
 import util.gen.c.function
 import rise.core.types.DataType._
+import shine.OpenCL.{GlobalSize, LocalSize}
 
 class gemvCheck extends test_util.Tests {
   private val N = 128
@@ -40,6 +43,21 @@ class gemvCheck extends test_util.Tests {
     ocl.gemvKeplerBest.toExpr
   }
 
+  test("OpenCL gemv versions host-code generation creates syntactically correct host-code"){
+
+    def run(e: ToBeTyped[Expr], localSize: LocalSize, globalSize: GlobalSize):String = {
+      val wrapped = autotune.wrapOclRun(localSize, globalSize)(e)
+      val codeModule = gen.opencl.hosted.fromExpr(wrapped)
+      shine.OpenCL.Module.translateToString(codeModule) // syntax checker is called here
+    }
+
+    run(ocl.gemvBlastN, LocalSize(64), GlobalSize(1024))
+    run(ocl.gemvBlastT, LocalSize(64), GlobalSize(1024))
+    run(ocl.gemvFused, LocalSize(128), GlobalSize(1024))
+    run(ocl.gemvFusedAMD, LocalSize(128), GlobalSize(1024))
+    run(ocl.gemvKeplerBest, LocalSize(128), GlobalSize(1024))
+  }
+
   test("OpenMP gemv versions type inference works") {
     omp.gemvFused.toExpr
   }