diff --git a/functions.go b/functions.go
index db5f2e1..728910b 100644
--- a/functions.go
+++ b/functions.go
@@ -90,6 +90,25 @@ func (s *State) RegisterGoFunction(name string, fn GoFunction) error {
 
 // UnregisterGoFunction removes a global function
 func (s *State) UnregisterGoFunction(name string) {
+	// First, find the function to get its pointer
+	s.GetGlobal(name)
+	if s.IsFunction(-1) {
+		// Get the first upvalue (function pointer)
+		if C.lua_getupvalue(s.L, -1, 1) != nil {
+			ptr := C.lua_touserdata(s.L, -1)
+			if ptr != nil {
+				// Remove from registry
+				functionRegistry.Lock()
+				delete(functionRegistry.funcs, ptr)
+				C.free(ptr)
+				functionRegistry.Unlock()
+			}
+			s.Pop(1) // Pop upvalue
+		}
+	}
+	s.Pop(1) // Pop function or nil
+
+	// Remove global
 	s.PushNil()
 	s.SetGlobal(name)
 }