diff --git a/CMakeLists.txt b/CMakeLists.txt
index 026634df..e0f64ce1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -89,3 +89,7 @@ if(PK_USE_CJSON)
     target_link_libraries(${PROJECT_NAME} PRIVATE cjson)
 endif()
 
+# link math library
+if(UNIX)
+    target_link_libraries(${PROJECT_NAME} PRIVATE m)
+endif()
\ No newline at end of file
diff --git a/build.sh b/build.sh
index a1387c71..a304428a 100644
--- a/build.sh
+++ b/build.sh
@@ -22,7 +22,7 @@ SRC=$(find src/ -name "*.c")
 
 echo "> Compiling and linking source files... "
 
-FLAGS="-std=c11 -O1 -Wfatal-errors -Iinclude"
+FLAGS="-std=c11 -O1 -Wfatal-errors -Iinclude -DNDEBUG"
 
 if [[ "$OSTYPE" == "darwin"* ]]; then
     LIB_EXTENSION=".dylib"
diff --git a/cmake_build.py b/cmake_build.py
index 30fb58a1..e7c3f8ae 100644
--- a/cmake_build.py
+++ b/cmake_build.py
@@ -18,17 +18,17 @@ assert config in ['Debug', 'Release', 'RelWithDebInfo']
 
 os.chdir("build")
 
-code = os.system(f"cmake .. -DPK_USE_CJSON=ON -DPK_ENABLE_OS=ON -DCMAKE_BUILD_TYPE={config}")
+code = os.system(f"cmake .. -DPK_ENABLE_OS=ON -DCMAKE_BUILD_TYPE={config}")
 assert code == 0
 code = os.system(f"cmake --build . --config {config}")
 assert code == 0
 
 if sys.platform == "win32":
     shutil.copy(f"{config}/main.exe", "../main.exe")
-    shutil.copy(f"{config}/pocketpy.dll", "../pocketpy.dll")
+    # shutil.copy(f"{config}/pocketpy.dll", "../pocketpy.dll")
 elif sys.platform == "darwin":
     shutil.copy("main", "../main")
-    shutil.copy("libpocketpy.dylib", "../libpocketpy.dylib")
+    # shutil.copy("libpocketpy.dylib", "../libpocketpy.dylib")
 else:
     shutil.copy("main", "../main")
-    shutil.copy("libpocketpy.so", "../libpocketpy.so")
+    # shutil.copy("libpocketpy.so", "../libpocketpy.so")
diff --git a/include/pocketpy/pocketpy.h b/include/pocketpy/pocketpy.h
index dfd06ba1..3f97fea8 100644
--- a/include/pocketpy/pocketpy.h
+++ b/include/pocketpy/pocketpy.h
@@ -460,7 +460,7 @@ bool py_call(py_Ref f, int argc, py_Ref argv) PY_RAISE;
 /// This function does extra checks to help you debug `py_CFunction`.
 bool py_callcfunc(py_CFunction f, int argc, py_Ref argv) PY_RAISE;
 #else
-#define py_callcfunc(f, argc, argv) f(argc, argv)
+#define py_callcfunc(f, argc, argv) (f((argc), (argv)))
 #endif
 
 /// Python equivalent to `str(val)`.
diff --git a/src/common/strname.c b/src/common/strname.c
index 42e52a1e..b0b270ad 100644
--- a/src/common/strname.c
+++ b/src/common/strname.c
@@ -17,7 +17,7 @@ void py_Name__initialize() {
     }
     c11_vector__ctor(&_r_interned, sizeof(c11_sv));
 
-#define MAGIC_METHOD(x) assert(x == py_name(#x));
+#define MAGIC_METHOD(x) if(x != py_name(#x)) abort();
 #include "pocketpy/xmacros/magics.h"
 #undef MAGIC_METHOD
 }
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index 20a8a684..31fd7dcf 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -17,7 +17,7 @@ static char* pk_default_import_file(const char* path) {
     long size = ftell(f);
     fseek(f, 0, SEEK_SET);
     char* buffer = malloc(size + 1);
-    fread(buffer, 1, size, f);
+    size = fread(buffer, 1, size, f);
     buffer[size] = 0;
     fclose(f);
     return buffer;
diff --git a/src/public/internal.c b/src/public/internal.c
index a416ea44..9da074e3 100644
--- a/src/public/internal.c
+++ b/src/public/internal.c
@@ -91,18 +91,22 @@ bool py_call(py_Ref f, int argc, py_Ref argv) {
     }
 }
 
+#if PK_DEBUG
 bool py_callcfunc(py_CFunction f, int argc, py_Ref argv) {
     py_StackRef p0 = py_peek(0);
     py_newnil(py_retval());
     bool ok = f(argc, argv);
     if(!ok) return false;
-    if(py_peek(0) != p0)
+    if(py_peek(0) != p0) {
         c11__abort("py_CFunction corrupts the stack! Did you forget to call `py_pop()`?");
-    if(py_isnil(py_retval()))
+    }
+    if(py_isnil(py_retval())) {
         c11__abort(
             "py_CFunction returns nothing! Did you forget to call `py_newnone(py_retval())`?");
+    }
     return true;
 }
+#endif
 
 bool py_vectorcall(uint16_t argc, uint16_t kwargc) {
     return VM__vectorcall(pk_current_vm, argc, kwargc, false) != RES_ERROR;
diff --git a/src/public/modules.c b/src/public/modules.c
index 574e9355..df580715 100644
--- a/src/public/modules.c
+++ b/src/public/modules.c
@@ -21,15 +21,14 @@ void py_setglobal(py_Name name, py_Ref val) { py_setdict(&pk_current_vm->main, n
 
 py_Ref py_newmodule(const char* path) {
     ManagedHeap* heap = &pk_current_vm->heap;
-    PyObject* obj = ManagedHeap__new(heap, tp_module, -1, 0);
 
     py_Ref r0 = py_pushtmp();
     py_Ref r1 = py_pushtmp();
 
     *r0 = (py_TValue){
-        .type = obj->type,
+        .type = tp_module,
         .is_ptr = true,
-        ._obj = obj,
+        ._obj = ManagedHeap__new(heap, tp_module, -1, 0),
     };
 
     int last_dot = c11_sv__rindex((c11_sv){path, strlen(path)}, '.');
diff --git a/src/public/stack_ops.c b/src/public/stack_ops.c
index 7bb0c9cb..49539a02 100644
--- a/src/public/stack_ops.c
+++ b/src/public/stack_ops.c
@@ -21,6 +21,9 @@ py_Ref py_getdict(py_Ref self, py_Name name) {
 
 void py_setdict(py_Ref self, py_Name name, py_Ref val) {
     assert(self && self->is_ptr);
+    // if(py_isidentical(self, &pk_current_vm->main)){
+    //     printf("Setting main: %s\n", py_name2str(name));
+    // }
     if(!py_ismagicname(name) || self->type != tp_type) {
         NameDict__set(PyObject__dict(self->_obj), name, *val);
     } else {
diff --git a/src2/main.c b/src2/main.c
index 094950a2..39d8f381 100644
--- a/src2/main.c
+++ b/src2/main.c
@@ -41,7 +41,11 @@ int main(int argc, char** argv) {
 
     if(argc == 1) {
         printf("pocketpy " PK_VERSION " (" __DATE__ ", " __TIME__ ") ");
-        printf("[%d bit] on %s\n", (int)(sizeof(void*) * 8), PY_SYS_PLATFORM_STRING);
+        printf("[%d bit] on %s", (int)(sizeof(void*) * 8), PY_SYS_PLATFORM_STRING);
+#if PK_DEBUG
+        printf(" (DEBUG)");
+#endif
+        printf("\n");
         printf("https://github.com/pocketpy/pocketpy\n");
         printf("Type \"exit()\" to exit.\n");
 
diff --git a/tests/00_tmp.py b/tests/00_tmp.py
deleted file mode 100644
index 05f0b0cb..00000000
--- a/tests/00_tmp.py
+++ /dev/null
@@ -1,7 +0,0 @@
-from cmath import isclose, sqrt
-
-res = sqrt(1+2j)
-assert isclose(res, 1.272019649514069+0.7861513777574233j)
-
-a = 1+2j
-{a: 1}
\ No newline at end of file