diff --git a/eolian/converters.py b/eolian/converters.py
index 5fd2b1c..a4ee43a 100644
--- a/eolian/converters.py
+++ b/eolian/converters.py
@@ -133,7 +133,9 @@ def conv_cls_name(cls):
 
 def convert_in_param(tp, param_name, is_nonull=None):
     c_type = tp.c_type
+    ptr = False
     if tp.type == eolian.TypeType.POINTER:
+        ptr = True
         tp = tp.base_type
         if tp.c_type in builtin_types:
             raise EolianTypeError("pointers to builtins currently not supported")
@@ -155,19 +157,25 @@ def convert_in_param(tp, param_name, is_nonull=None):
     if keyword.iskeyword(param_name):
         param_name += "_"
 
+    conv_param_name = None
+
     conv_expr_2 = conversions_in_c.get(key)
     if conv_expr_2 is not None:
-        param_name = conv_expr_2.format(param_name)
+        conv_param_name = conv_expr_2.format(param_name)
 
     conv_t = mapping_in[key]
     if conv_t is None:
         # conv_t = ""
         conv_t = ""
 
-    if not is_nonull:
-        key = "<{0}>{1} if {1} is not None else NULL".format(c_type, param_name)
+    if ptr and not is_nonull:
+        conv_param_name = "<{0}>{1} if {2} is not None else NULL".format(
+            c_type,
+            conv_param_name if conv_param_name else param_name,
+            param_name
+            )
 
-    return conv_expr_1, conv_t, param_name
+    return conv_expr_1, conv_t, conv_param_name if conv_param_name else param_name
 
 
 def convert_out_param(tp, param_name):
diff --git a/examples/eolian-example.py b/examples/eolian-example.py
index 353e17a..7c46383 100755
--- a/examples/eolian-example.py
+++ b/examples/eolian-example.py
@@ -27,7 +27,7 @@ img = elm.Image(win)
 img.size_hint_weight = (1.0, 1.0)
 img.smooth = True
 img.aspect_fixed = True
-img.file = sys.argv[1], ""
+img.file = sys.argv[1], None
 img.position = (0, 0)
 img.size = (w, h)
 
@@ -38,7 +38,7 @@ def _mouse_down_cb(*args):
     if file_idx > len(sys.argv):
         file_idx = 1
     global img
-    img.file = sys.argv[file_idx], ""
+    img.file = sys.argv[file_idx], None
     return True
 
 img.event_callback_add("mouse,down", _mouse_down_cb)