diff --git a/filecloudapi/fcserver.py b/filecloudapi/fcserver.py
index dd877e6..521cd5d 100644
--- a/filecloudapi/fcserver.py
+++ b/filecloudapi/fcserver.py
@@ -817,10 +817,10 @@ def close(self):
             }
 
             if nofileoverwrite is not None:
-                params["nofileoverwrite"] = "true" if nofileoverwrite else "false"
+                params["nofileoverwrite"] = 1 if nofileoverwrite else 0
 
             if iflastmodified is not None:
-                params["iflastmodified"] = self._serverdatetime(iflastmodified)
+                params["iflastmodified"] = str(int(iflastmodified.timestamp()))
 
             params_str = urlencode(params)
 
@@ -865,10 +865,10 @@ def close(self):
             }
 
             if nofileoverwrite is not None:
-                params["nofileoverwrite"] = "true" if nofileoverwrite else "false"
+                params["nofileoverwrite"] = 1 if nofileoverwrite else 0
 
             if iflastmodified is not None:
-                params["iflastmodified"] = self._serverdatetime(iflastmodified)
+                params["iflastmodified"] = str(int(iflastmodified.timestamp()))
 
             if data_size is not None:
                 params["filesize"] = data_size
diff --git a/pyproject.toml b/pyproject.toml
index 8fe56b3..e5173fa 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [tool.poetry]
 
 name = "filecloudapi-python"
-version = "0.4.0"
+version = "0.4.1"
 description = "A Python library to connect to a Filecloud server"
 
 packages = [{ include = "filecloudapi" }]