diff --git a/server/src/lsp_server.py b/server/src/lsp_server.py
index 4e2b91b..1d5893d 100644
--- a/server/src/lsp_server.py
+++ b/server/src/lsp_server.py
@@ -213,6 +213,10 @@ def did_change(params: lsp.DidChangeTextDocumentParams) -> None:
     """LSP handler for textDocument/didChange request"""
     document = LSP_SERVER.workspace.get_text_document(params.text_document.uri)
     LSP_SERVER.compute_diagnostics(document)
+    ci = _Completion()
+    tree = LSP_SERVER.parser.parse(document.source)
+    tree.accept(ci, recurse=True)
+    LSP_SERVER._custom_functions = ci.custom_functions
 
 
 @LSP_SERVER.feature(
@@ -243,15 +247,12 @@ def document_diagnostic(params: lsp.DocumentDiagnosticParams):
 @LSP_SERVER.feature(lsp.TEXT_DOCUMENT_COMPLETION)
 def on_completion(params: lsp.CompletionParams) -> list[lsp.CompletionItem]:
     document = LSP_SERVER.workspace.get_text_document(params.text_document.uri)
-    ci = _Completion()
-    tree = LSP_SERVER.parser.parse(document.source)
-    tree.accept(ci, recurse=True)
 
     items = (
         standard_items.tcl_keyword_list
         + standard_items.nx_procs
         + standard_items.nx_variables
-        + ci.custom_functions
+        + LSP_SERVER._custom_functions
     )
     return lsp.CompletionList(is_incomplete=False, items=items)
 
diff --git a/server/src/tools/completion_items.py b/server/src/tools/completion_items.py
index 39fc1c9..0e5aba3 100644
--- a/server/src/tools/completion_items.py
+++ b/server/src/tools/completion_items.py
@@ -29,7 +29,9 @@ class _Completion(Visitor):
 
         if routine.contents == "proc" and command.args:
             first_arg = command.args[0]
-            if hasattr(first_arg, "value"):
+            if hasattr(first_arg, "value") and not any(
+                item.label == first_arg.value for item in self._custom_functions
+            ):
                 self._custom_functions.append(
                     lsp.CompletionItem(
                         label=first_arg.value, kind=lsp.CompletionItemKind.Function