diff --git a/kiss/src/kiss/CompilerTools.hx b/kiss/src/kiss/CompilerTools.hx
index 4574b709..804f7a94 100644
--- a/kiss/src/kiss/CompilerTools.hx
+++ b/kiss/src/kiss/CompilerTools.hx
@@ -1,12 +1,13 @@
 package kiss;
 
-
 #if macro
 import kiss.Kiss;
 import kiss.Helpers;
 import sys.FileSystem;
 import sys.io.File;
 import haxe.io.Path;
+import haxe.macro.Expr;
+import haxe.macro.Context;
 
 using StringTools;
 using haxe.io.Path;
@@ -38,9 +39,9 @@ typedef CompilationArgs = {
 class CompilerTools {
     /**
      * Compile a kiss file into a standalone script.
-     * @return A function that, when called, executes the script and returns the script output as a string.
+     * @return An expression of a function that, when called, executes the script and returns the script output as a string.
      */
-    public static function compileFileToScript(kissFile:String, args:CompilationArgs):() -> String {
+    public static function compileFileToScript(kissFile:String, args:CompilationArgs):Expr {
         var k = Kiss.defaultKissState();
         var beginExpsInFile = Kiss.load(kissFile, k, "", true);
         return compileToScript([beginExpsInFile], args);
@@ -48,9 +49,9 @@ class CompilerTools {
 
     /**
      * Compile kiss expressions into a standalone script
-     * @return A function that, when called, executes the script and returns the script output as a string.
+     * @return An expression of a function that, when called, executes the script and returns the script output as a string.
      */
-    public static function compileToScript(exps:Array<ReaderExp>, args:CompilationArgs):() -> String {
+    public static function compileToScript(exps:Array<ReaderExp>, args:CompilationArgs):Expr {
         // if folder exists, delete it
         if (FileSystem.exists(args.outputFolder)) {
             for (file in FileSystem.readDirectory(args.outputFolder)) {
@@ -75,7 +76,7 @@ class CompilerTools {
                 copyToFolder(file);
             }
         }
-        
+
         // If a main haxe file was given, use it
         var mainHxFile = if (args.mainHxFile != null) {
             args.mainHxFile;
@@ -113,16 +114,16 @@ class CompilerTools {
 
         // run haxelib install on given hxml and generated hxml
         var hxmlFiles = [buildHxmlFile];
-        Helpers.assertProcess("haxelib", ["install", "--always", buildHxmlFile]);
+        Prelude.assertProcess("haxelib", ["install", "--always", buildHxmlFile]);
         if (args.hxmlFile != null) {
             hxmlFiles.push(args.hxmlFile);
-            Helpers.assertProcess("haxelib", ["install", "--always", args.hxmlFile]);
+            Prelude.assertProcess("haxelib", ["install", "--always", args.hxmlFile]);
         }
 
         // TODO install language-specific dependencies from langProjectFile (which might be tricky because we can't set the working directory)
 
         // Compile the script
-        Helpers.assertProcess("haxe", ["--cwd", args.outputFolder].concat(hxmlFiles.map(Path.withoutDirectory)));
+        Prelude.assertProcess("haxe", ["--cwd", args.outputFolder].concat(hxmlFiles.map(Path.withoutDirectory)));
 
         var command = "";
         var scriptExt = "";
@@ -134,9 +135,11 @@ class CompilerTools {
                 command = "python";
                 scriptExt = "py";
         }
- 
-        // return lambda that calls new Process() that runs the target-specific file
-        return () -> Helpers.assertProcess(command, [Path.join([args.outputFolder, '$mainClassName.$scriptExt'])]);
+
+        // return an expression for a lambda that calls new Process() that runs the target-specific file
+        var callingCode = '() -> kiss.Prelude.assertProcess("$command", [haxe.io.Path.join(["${args.outputFolder}", "$mainClassName.$scriptExt"])])';
+        trace(callingCode);
+        return Context.parse(callingCode, Context.currentPos());
     }
 }
 #end
diff --git a/kiss/src/kiss/Helpers.hx b/kiss/src/kiss/Helpers.hx
index f47775fe..b2130b65 100644
--- a/kiss/src/kiss/Helpers.hx
+++ b/kiss/src/kiss/Helpers.hx
@@ -496,16 +496,6 @@ class Helpers {
 
     // Get the path to a haxelib the user has installed
     public static function libPath(haxelibName:String) {
-        return assertProcess("haxelib", ["libpath", haxelibName]);
-    }
-
-    public static function assertProcess(command:String, args:Array<String>):String {
-        var p = new Process(command, args);
-        switch (p.exitCode()) {
-            case 0:
-                return p.stdout.readAll().toString().trim();
-            default:
-                throw p.stderr.readAll().toString().trim();
-        }
+        return Prelude.assertProcess("haxelib", ["libpath", haxelibName]);
     }
 }
diff --git a/kiss/src/kiss/Kiss.hx b/kiss/src/kiss/Kiss.hx
index 1b5f3390..cd0b4ea9 100644
--- a/kiss/src/kiss/Kiss.hx
+++ b/kiss/src/kiss/Kiss.hx
@@ -73,6 +73,7 @@ class Kiss {
                 "has" => Symbol("Lambda.has"),
                 "count" => Symbol("Lambda.count"),
                 "enumerate" => Symbol("Prelude.enumerate"),
+                "assertProcess" => Symbol("Prelude.assertProcess"),
                 // These work with (apply) because they are added as "opAliases" in Macros.kiss:
                 "min" => Symbol("Prelude.min"),
                 "max" => Symbol("Prelude.max"),
diff --git a/kiss/src/kiss/Prelude.hx b/kiss/src/kiss/Prelude.hx
index 2c154abf..7a5c839e 100644
--- a/kiss/src/kiss/Prelude.hx
+++ b/kiss/src/kiss/Prelude.hx
@@ -367,8 +367,8 @@ class Prelude {
         #if (!macro && hxnodejs)
         var kissProcess = ChildProcess.spawnSync("haxelib", ["run", "kiss", "convert", "--all", "--hscript"], {input: '${kissStr}\n'});
         if (kissProcess.status != 0) {
-            var error:String = kissProcess.stderr;
-            throw 'failed to convert ${kissStr} to hscript: ${error}';
+            var error:Buffer = kissProcess.stderr;
+            throw 'failed to convert ${kissStr} to hscript: ${error.toString()}';
         }
         var output:Buffer = kissProcess.stdout;
         return output.toString();
@@ -392,4 +392,28 @@ class Prelude {
         throw "Can't convert Kiss to HScript on this target.";
         #end
     }
+
+    public static function assertProcess(command:String, args:Array<String>):String {
+        #if sys
+        var p = new Process(command, args);
+        switch (p.exitCode()) {
+            case 0:
+                return p.stdout.readAll().toString().trim();
+            default:
+                throw p.stderr.readAll().toString().trim();
+        }
+        #elseif hxnodejs
+        var p = ChildProcess.spawnSync(command, args);
+        switch (p.status) {
+            case 0:
+                var output:Buffer = p.stdout;
+                return output.toString();
+            default:
+                var error:String = p.stderr;
+                throw error;
+        }
+        #else
+        throw "Can't run a subprocess on this target."
+        #end
+    }
 }
diff --git a/kiss/src/test/cases/CompilerToolsTestCase.hx b/kiss/src/test/cases/CompilerToolsTestCase.hx
index 5734b837..e7d037bb 100644
--- a/kiss/src/test/cases/CompilerToolsTestCase.hx
+++ b/kiss/src/test/cases/CompilerToolsTestCase.hx
@@ -10,37 +10,27 @@ import haxe.macro.Context;
 
 class CompilerToolsTestCase extends Test {
     function testCompileHelloWorldJs() {
-        Assert.equals("Hello world!", _testCompileHelloWorldJs());
+        Assert.equals("Hello world!", _testCompileHelloWorldJs()());
     }
 
     static macro function _testCompileHelloWorldJs() {
-        var runHelloWorld = CompilerTools.compileFileToScript(
+        return CompilerTools.compileFileToScript(
             "kiss/template/src/template/Main.kiss", {
                 lang: JavaScript,
                 outputFolder: "bin/helloWorldJsTest",
             });
-
-        return {
-            pos: Context.currentPos(),
-            expr: EConst(CString(runHelloWorld(), DoubleQuotes))
-        };
     }
 
     function testCompileHelloWorldPy() {
-        Assert.equals("Hello world!", _testCompileHelloWorldPy());
+        Assert.equals("Hello world!", _testCompileHelloWorldPy()());
     }
 
     static macro function _testCompileHelloWorldPy() {
-        var runHelloWorld = CompilerTools.compileFileToScript(
+        return CompilerTools.compileFileToScript(
             "kiss/template/src/template/Main.kiss", {
                 lang: Python,
                 outputFolder: "bin/helloWorldPyTest",
             });
-
-        return {
-            pos: Context.currentPos(),
-            expr: EConst(CString(runHelloWorld(), DoubleQuotes))
-        };
     }
 
     // TODO test what happens when passing more arguments/files