diff --git a/src/ODEInterfaceDiffEq.jl b/src/ODEInterfaceDiffEq.jl
index d88ec28..6f3b56b 100644
--- a/src/ODEInterfaceDiffEq.jl
+++ b/src/ODEInterfaceDiffEq.jl
@@ -19,8 +19,6 @@ end
 
 @compat const KW = Dict{Symbol,Any}
 
-const InterpFunction = FunctionWrappers.FunctionWrapper{Vector{Float64},Tuple{Float64}}
-
 include("algorithms.jl")
 include("integrator_types.jl")
 include("integrator_utils.jl")
diff --git a/src/callbacks.jl b/src/callbacks.jl
index 2f0e7c9..bd0f121 100644
--- a/src/callbacks.jl
+++ b/src/callbacks.jl
@@ -53,10 +53,10 @@ end
     # of the true value due to it being =0 sans floating point issues.
 
     if !(typeof(callback.idxs) <: Number)
-      tmp = integrator(integrator.tprev+100eps(typeof(integrator.tprev)))
+      tmp = integrator(integrator.tprev+100eps(typeof(integrator.tprev)))::Vector{Float64}
       callback.idxs == nothing ? _tmp = tmp : _tmp = @view tmp[callback.idxs]
     else
-      _tmp = integrator(integrator.tprev+100eps(typeof(integrator.tprev)))[callback.idxs]
+      _tmp = integrator((integrator.tprev+100eps(typeof(integrator.tprev)))::Vector{Float64})[callback.idxs]
     end
 
     tmp_condition = callback.condition(_tmp,integrator.tprev +
@@ -82,10 +82,10 @@ end
   elseif callback.interp_points!=0  # Use the interpolants for safety checking
     for i in 2:length(Θs)
       if !(typeof(callback.idxs) <: Number)
-        tmp = integrator(integrator.tprev+dt*Θs[i])
+        tmp = integrator(integrator.tprev+dt*Θs[i])::Vector{Float64}
         callback.idxs == nothing ? _tmp = tmp : _tmp = @view tmp[callback.idxs]
       else
-        _tmp = integrator(integrator.tprev+dt*Θs[i])[callback.idxs]
+        _tmp = (integrator(integrator.tprev+dt*Θs[i])::Vector{Float64})[callback.idxs]
       end
       new_sign = callback.condition(_tmp,integrator.tprev+dt*Θs[i],integrator)
       if prev_sign == 0
@@ -119,10 +119,10 @@ function find_callback_time(integrator,callback)
       if callback.rootfind
         zero_func = (Θ) -> begin
           if !(typeof(callback.idxs) <: Number)
-            tmp = integrator(integrator.tprev+Θ*dt)
+            tmp = integrator(integrator.tprev+Θ*dt)::Vector{Float64}
             callback.idxs == nothing ? _tmp = tmp : _tmp = @view tmp[callback.idxs]
           else
-            _tmp = integrator(integrator.tprev+Θ*dt)[callback.idxs]
+            _tmp = (integrator(integrator.tprev+Θ*dt)::Vector{Float64})[callback.idxs]
           end
           out = callback.condition(tmp,integrator.tprev+Θ*dt,integrator)
           out
@@ -153,7 +153,7 @@ end
 function apply_callback!(integrator,callback::ContinuousCallback,cb_time,prev_sign)
   if cb_time != zero(typeof(integrator.t))
     integrator.t = integrator.tprev+cb_time
-    tmp = integrator(integrator.t)
+    tmp = integrator(integrator.t)::Vector{Float64}
     if eltype(integrator.sol.u) <: Vector
         integrator.u .= tmp
     else
diff --git a/src/integrator_types.jl b/src/integrator_types.jl
index 351c06b..71db006 100644
--- a/src/integrator_types.jl
+++ b/src/integrator_types.jl
@@ -14,7 +14,7 @@ mutable struct ODEInterfaceIntegrator{uType,uPrevType,oType,SType,solType} <: Di
     tdir::Float64
     sizeu::SType
     sol::solType
-    eval_sol_fcn::InterpFunction
+    eval_sol_fcn
     event_last_time::Bool
 end
 
diff --git a/src/integrator_utils.jl b/src/integrator_utils.jl
index 24eaf4f..3d92d19 100644
--- a/src/integrator_utils.jl
+++ b/src/integrator_utils.jl
@@ -14,7 +14,7 @@ function handle_callbacks!(integrator,eval_sol_fcn)
       integrator.event_last_time = true
       continuous_modified,saved_in_cb = apply_callback!(integrator,continuous_callbacks[idx],time,upcrossing)
     else
-      integrator.event_last_time = false 
+      integrator.event_last_time = false
     end
   end
   if !(typeof(discrete_callbacks)<:Tuple{})
@@ -38,7 +38,7 @@ function DiffEqBase.savevalues!(integrator::ODEInterfaceIntegrator,force_save=fa
   while !isempty(integrator.opts.saveat) &&
       integrator.tdir*top(integrator.opts.saveat) < integrator.tdir*integrator.t
       curt = pop!(integrator.opts.saveat)
-      tmp = integrator(curt)
+      tmp = integrator(curt)::Vector{Float64}
       push!(integrator.sol.t,curt)
       save_value!(integrator.sol.u,tmp,uType,integrator.sizeu)
   end
diff --git a/src/solve.jl b/src/solve.jl
index 1ce42da..127d155 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -72,7 +72,7 @@ function solve{uType,tuptType,isinplace,AlgType<:ODEInterfaceAlgorithm}(
     opts = DEOptions(saveat_internal,save_everystep,callbacks_internal)
     integrator = ODEInterfaceIntegrator(u,uprev,tspan[1],tspan[1],opts,
                                         false,tdir,sizeu,sol,
-                                        InterpFunction((t)->[t]),false)
+                                        (t)->[t],false)
 
     outputfcn = OutputFunction(integrator)
     o[:OUTPUTFCN] = outputfcn
@@ -326,7 +326,7 @@ function (f::OutputFunction)(reason::ODEInterface.OUTPUTFCN_CALL_REASON,
       end
       integrator.t = t
       integrator.tprev = tprev
-      integrator.eval_sol_fcn = InterpFunction(eval_sol_fcn)
+      integrator.eval_sol_fcn = eval_sol_fcn
 
       handle_callbacks!(integrator,eval_sol_fcn)
 
diff --git a/test/algorithm_tests.jl b/test/algorithm_tests.jl
index e4d81dd..a40b86f 100644
--- a/test/algorithm_tests.jl
+++ b/test/algorithm_tests.jl
@@ -1,5 +1,4 @@
-using ODEInterfaceDiffEq, DiffEqProblemLibrary, DiffEqBase
-using Base.Test
+using ODEInterfaceDiffEq, DiffEqProblemLibrary, DiffEqBase, Test
 
 prob = prob_ode_linear
 sol =solve(prob,dopri5(),dt=1//2^(4))