diff --git a/vala/step2_eval.vala b/vala/step2_eval.vala
index fec151503a..f62e8806a2 100644
--- a/vala/step2_eval.vala
+++ b/vala/step2_eval.vala
@@ -101,11 +101,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step3_env.vala b/vala/step3_env.vala
index bfced742ba..429b5b17db 100644
--- a/vala/step3_env.vala
+++ b/vala/step3_env.vala
@@ -83,11 +83,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step4_if_fn_do.vala b/vala/step4_if_fn_do.vala
index 13ab98aa2a..93d09c3f58 100644
--- a/vala/step4_if_fn_do.vala
+++ b/vala/step4_if_fn_do.vala
@@ -38,11 +38,12 @@ class Mal.Main: GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step5_tco.vala b/vala/step5_tco.vala
index d944f4ab25..c29a31fd6d 100644
--- a/vala/step5_tco.vala
+++ b/vala/step5_tco.vala
@@ -38,11 +38,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step6_file.vala b/vala/step6_file.vala
index 23979477fd..3bdd83c96e 100644
--- a/vala/step6_file.vala
+++ b/vala/step6_file.vala
@@ -52,11 +52,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step7_quote.vala b/vala/step7_quote.vala
index 57739e1f02..4fc745f914 100644
--- a/vala/step7_quote.vala
+++ b/vala/step7_quote.vala
@@ -52,11 +52,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step8_macros.vala b/vala/step8_macros.vala
index 099562e544..8c0088cb6c 100644
--- a/vala/step8_macros.vala
+++ b/vala/step8_macros.vala
@@ -52,11 +52,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/step9_try.vala b/vala/step9_try.vala
index 155690caee..f6d5222d58 100644
--- a/vala/step9_try.vala
+++ b/vala/step9_try.vala
@@ -53,11 +53,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();
diff --git a/vala/stepA_mal.vala b/vala/stepA_mal.vala
index 46eab4d266..349c607840 100644
--- a/vala/stepA_mal.vala
+++ b/vala/stepA_mal.vala
@@ -53,11 +53,12 @@ class Mal.Main : GLib.Object {
             return result;
         }
         if (ast is Mal.Vector) {
-            var results = new GLib.List<Mal.Val>();
-            for (var iter = (ast as Mal.Vector).iter();
-                 iter.nonempty(); iter.step())
-                results.append(EVAL(iter.deref(), env));
-            return new Mal.Vector.from_list(results);
+            var vec = ast as Mal.Vector;
+            var result = new Mal.Vector.with_size(vec.length);
+            var root = new GC.Root(result); (void)root;
+            for (var i = 0; i < vec.length; i++)
+                result[i] = EVAL(vec[i], env);
+            return result;
         }
         if (ast is Mal.Hashmap) {
             var result = new Mal.Hashmap();