diff --git a/src/types.jl b/src/types.jl
index dbb5d05..07327eb 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -122,13 +122,13 @@ function DP5Solver(
     f, 
     x::Real, 
     y::AbstractVector; kw...)
-    k1 = copy(y)
-    k2 = copy(y)
-    k3 = copy(y)
-    k4 = copy(y)
-    k5 = copy(y)
-    k6 = copy(y)
-    y1 = copy(y)
+    k1 = similar(y)
+    k2 = similar(y)
+    k3 = similar(y)
+    k4 = similar(y)
+    k5 = similar(y)
+    k6 = similar(y)
+    y1 = similar(y)
     ysti = copy(y)
     DP5Solver(f, x, y, k1, k2, k3, k4, k5, k6, y1, ysti;kw...)
 end
@@ -194,17 +194,17 @@ function DP8Solver(
     f, 
     x::Real, 
     y::AbstractVector; kw...)
-    k1 = copy(y)
-    k2 = copy(y)
-    k3 = copy(y)
-    k4 = copy(y)
-    k5 = copy(y)
-    k6 = copy(y)
-    k7 = copy(y)
-    k8 = copy(y)
-    k9 = copy(y)
-    k10 = copy(y)
-    y1 = copy(y)
+    k1 = similar(y)
+    k2 = similar(y)
+    k3 = similar(y)
+    k4 = similar(y)
+    k5 = similar(y)
+    k6 = similar(y)
+    k7 = similar(y)
+    k8 = similar(y)
+    k9 = similar(y)
+    k10 = similar(y)
+    y1 = similar(y)
     DP8Solver(f, x, y, k1, k2, k3, k4, k5, k6, k7, k8, k9, k10, y1;kw...)
 end