diff --git a/modules/gdscript/gdscript.cpp b/modules/gdscript/gdscript.cpp
index 51a5584920fa..477b1c0e2b3c 100644
--- a/modules/gdscript/gdscript.cpp
+++ b/modules/gdscript/gdscript.cpp
@@ -2079,6 +2079,10 @@ String GDScriptWarning::get_message() const {
 			CHECK_SYMBOLS(1);
 			return "Function declaration of '" + symbols[0] + "()' conflicts with a constant of the same name.";
 		} break;
+		case FUNCTION_OVERRIDES_INTERNAL_CALLBACK: {
+			CHECK_SYMBOLS(1);
+			return "Function declaration '" + symbols[0] + "()' overrides internal callback.";
+		} break;
 		case INCOMPATIBLE_TERNARY: {
 			return "Values of the ternary conditional are not mutually compatible.";
 		} break;
@@ -2158,6 +2162,7 @@ String GDScriptWarning::get_name_from_code(Code p_code) {
 		"VARIABLE_CONFLICTS_FUNCTION",
 		"FUNCTION_CONFLICTS_VARIABLE",
 		"FUNCTION_CONFLICTS_CONSTANT",
+		"FUNCTION_OVERRIDES_INTERNAL_CALLBACK",
 		"INCOMPATIBLE_TERNARY",
 		"UNUSED_SIGNAL",
 		"RETURN_VALUE_DISCARDED",
diff --git a/modules/gdscript/gdscript.h b/modules/gdscript/gdscript.h
index 029a5ba9b803..6b0077db7758 100644
--- a/modules/gdscript/gdscript.h
+++ b/modules/gdscript/gdscript.h
@@ -292,6 +292,7 @@ struct GDScriptWarning {
 		VARIABLE_CONFLICTS_FUNCTION, // Variable has the same name of a function
 		FUNCTION_CONFLICTS_VARIABLE, // Function has the same name of a variable
 		FUNCTION_CONFLICTS_CONSTANT, // Function has the same name of a constant
+		FUNCTION_OVERRIDES_INTERNAL_CALLBACK, // Function has the same name of an internal callback prefixed with "_".
 		INCOMPATIBLE_TERNARY, // Possible values of a ternary if are not mutually compatible
 		UNUSED_SIGNAL, // Signal is defined but never emitted
 		RETURN_VALUE_DISCARDED, // Function call returns something but the value isn't used
diff --git a/modules/gdscript/gdscript_parser.cpp b/modules/gdscript/gdscript_parser.cpp
index daf74fa7e73a..1f8c17c527df 100644
--- a/modules/gdscript/gdscript_parser.cpp
+++ b/modules/gdscript/gdscript_parser.cpp
@@ -5628,6 +5628,23 @@ void GDScriptParser::_determine_inheritance(ClassNode *p_class, bool p_recursive
 			_determine_inheritance(p_class->subclasses[i], p_recursive);
 		}
 	}
+#ifdef DEBUG_METHODS_ENABLED
+	// Check whether script functions override any private callbacks in ClassDB.
+	List<MethodInfo> virtuals;
+	ClassDB::get_virtual_methods(p_class->base_type.native_type, &virtuals);
+	for (int i = 0; i < p_class->functions.size(); i++) {
+		for (const List<MethodInfo>::Element *E = virtuals.front(); E; E = E->next()) {
+			String func_name = p_class->functions[i]->name;
+			if (func_name == E->get().name) {
+				continue; // Overridding virtual methods is the way to go, skip.
+			}
+			if (func_name.begins_with("_") && ClassDB::has_method(p_class->base_type.native_type, func_name)) {
+				_add_warning(GDScriptWarning::FUNCTION_OVERRIDES_INTERNAL_CALLBACK, -1, func_name);
+				break;
+			}
+		}
+	}
+#endif // DEBUG_METHODS_ENABLED
 }
 
 String GDScriptParser::DataType::to_string() const {