diff --git a/build.bat b/build.bat
new file mode 100644
index 0000000..1d52bfc
--- /dev/null
+++ b/build.bat
@@ -0,0 +1,2 @@
+call "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliary\Build\vcvarsall.bat" x64
+cl /O2 src\coparun\runmem.c src\coparun\coparun.c src\coparun\mem_man.c /Fe:bin\coparun.exe
\ No newline at end of file
diff --git a/src/copapy/__init__.py b/src/copapy/__init__.py
index dbb7ce2..457a01f 100644
--- a/src/copapy/__init__.py
+++ b/src/copapy/__init__.py
@@ -354,6 +354,7 @@ def compile_to_instruction_list(node_list: Iterable[Node], sdb: stencil_database
 
         for variable in variable_list:
             lengths = sdb.var_size['dummy_' + variable.dtype]
+            print('variable_mem_layout', variable.dtype, lengths)
             object_list.append((variable, offset, lengths))
             offset += (lengths + 3) // 4 * 4
 
@@ -460,6 +461,7 @@ class Target():
     def read_value(self, net: Net) -> float | int:
         assert net in self._variables, f"Variable {net} not found"
         addr, lengths, var_type = self._variables[net]
+        print('read_value', addr, lengths)
         data = read_data_mem(addr, lengths)
         assert data is not None and len(data) == lengths, f"Failed to read variable {net}"
         en = {'little': '<', 'big': '>'}[self.sdb.byteorder]
@@ -481,12 +483,17 @@ class Target():
                 raise ValueError(f"Unsupported int length: {lengths} bytes")
         else:
             raise ValueError(f"Unsupported variable type: {var_type}")
+        
 
     def read_variable_remote(self, net: Net) -> None:
-        assert net in self._variables, f"Variable {net} not found in data writer variables"
-        addr, lengths, _ = self._variables[net]
         dw = binw.data_writer(self.sdb.byteorder)
-        dw.write_com(binw.Command.READ_DATA)
-        dw.write_int(addr)
-        dw.write_int(lengths)
+        add_read_command(dw, self._variables, net)
         assert coparun(dw.get_data()) > 0
+
+def add_read_command(dw: binw.data_writer, variables: dict[Net, tuple[int, int, str]], net: Net) -> None:
+    assert net in variables, f"Variable {net} not found in data writer variables"
+    addr, lengths, _ = variables[net]
+    dw.write_com(binw.Command.READ_DATA)
+    dw.write_int(addr)
+    dw.write_int(lengths)
+    
diff --git a/src/coparun/runmem.c b/src/coparun/runmem.c
index 27f8d7d..197b7ae 100644
--- a/src/coparun/runmem.c
+++ b/src/coparun/runmem.c
@@ -38,7 +38,7 @@ int parse_commands(uint8_t *bytes) {
     uint32_t command;
     uint32_t reloc_type;
     uint32_t offs;
-    int data_offs;
+    ptrdiff_t data_offs;
     uint32_t size;
     int err_flag = 0;
     uint32_t rel_entr_point;
@@ -89,7 +89,7 @@ int parse_commands(uint8_t *bytes) {
                 offs = *(uint32_t*)bytes; bytes += 4;
                 reloc_type = *(uint32_t*)bytes; bytes += 4;
                 value = *(int32_t*)bytes; bytes += 4;
-                data_offs = (int32_t)(data_memory - executable_memory);
+                data_offs = data_memory - executable_memory;
                 printf("PATCH_OBJECT patch_offs=%i reloc_type=%i value=%i data_offs=%i\n",
                     offs, reloc_type, value, data_offs);
                 if (abs(data_offs) > 0x7FFFFFFF) {
diff --git a/tests/test_coparun_module.py b/tests/test_coparun_module.py
index 58142e0..9df01a1 100644
--- a/tests/test_coparun_module.py
+++ b/tests/test_coparun_module.py
@@ -1,6 +1,6 @@
 from copapy import const, Target
 from pytest import approx
-
+import time
 
 def function(c1, c2):
     i1 = c1 * 3.3 + 5
@@ -19,14 +19,17 @@ def test_compile():
     ret = function(c1, c2)
 
     tg = Target()
+    print('* compile and copy ...')
     tg.compile(ret)
-    tg.run()
+    #time.sleep(5)
+    print('* run and copy ...')
+    #tg.run()
+    #print('* finished')
 
     ret_ref = function(4, 2)
 
-    print()
-
     for test, ref, name in zip(ret, ret_ref, ['i1', 'i2', 'r1', 'r2']):
+        print('+', name)
         assert tg.read_value(test) == approx(ref, 1e-5), name
 
 
diff --git a/tests/test_crash_win.py b/tests/test_crash_win.py
new file mode 100644
index 0000000..070287b
--- /dev/null
+++ b/tests/test_crash_win.py
@@ -0,0 +1,56 @@
+from copapy import Write, const
+import copapy
+import subprocess
+import struct
+from copapy import binwrite
+
+
+def run_command(command: list[str], encoding: str = 'utf8') -> str:
+    process = subprocess.Popen(command, stdout=subprocess.PIPE)
+    output, error = process.communicate()
+
+    assert error is None, f"Error occurred: {error.decode(encoding)}"
+    return output.decode(encoding)
+
+
+def function(c1, c2):
+    i1 = c1 * 3.3 + 5
+    i2 = c2 * 5 + c1
+    r1 = i1 + i2 * 55 / 4
+    r2 = 4 * i2 + 5
+
+    return i1, i2, r1, r2 
+
+
+def test_compile():
+
+    c1 = const(4)
+    c2 = const(2)
+    
+    ret = function(c1, c2)
+
+    dw, variable_list = copapy.compile_to_instruction_list([Write(net) for net in ret], copapy.generic_sdb)
+
+    # run program command
+    dw.write_com(binwrite.Command.RUN_PROG)
+    dw.write_int(0)
+
+    dw.write_com(binwrite.Command.READ_DATA)
+    dw.write_int(0)
+    dw.write_int(36)
+
+    for net, name in zip(ret, ['i1', 'i2', 'r1', 'r2']):
+        print('+', name)
+        copapy.add_read_command(dw, variable_list, net)
+
+    dw.write_com(binwrite.Command.END_PROG)
+
+    dw.to_file('bin/test.copapy')
+    result = run_command(['bin/coparun', 'bin/test.copapy'])
+    print('* Output from runner:')
+    print(result)
+    assert 'Return value: 1' in result
+
+if __name__ == "__main__":
+    #test_example()
+    test_compile()