diff --git a/modules/gdscript/doc_classes/@GDScript.xml b/modules/gdscript/doc_classes/@GDScript.xml
index 304c72f086c..de45e387cde 100644
--- a/modules/gdscript/doc_classes/@GDScript.xml
+++ b/modules/gdscript/doc_classes/@GDScript.xml
@@ -90,14 +90,18 @@
 			</return>
 			<argument index="0" name="condition" type="bool">
 			</argument>
+			<argument index="1" name="message" type="String" default="&quot;&quot;">
+			</argument>
 			<description>
-				Asserts that the [code]condition[/code] is [code]true[/code] . If the [code]condition[/code] is [code]false[/code], an error is generated and the program is halted until you resume it. Only executes in debug builds, or when running the game from the editor. Use it for debugging purposes, to make sure a statement is [code]true[/code] during development.
+				Asserts that the [code]condition[/code] is [code]true[/code]. If the [code]condition[/code] is [code]false[/code], an error is generated and the program is halted until you resume it. Only executes in debug builds, or when running the game from the editor. Use it for debugging purposes, to make sure a statement is [code]true[/code] during development.
+				The optional [code]message[/code] argument, if given, is shown in addition to the generic "Assertion failed" message. You can use this to provide additional details about why the assertion failed.
 				[codeblock]
 				# Imagine we always want speed to be between 0 and 20
 				speed = -10
 				assert(speed &lt; 20) # True, the program will continue
 				assert(speed &gt;= 0) # False, the program will stop
 				assert(speed &gt;= 0 &amp;&amp; speed &lt; 20) # You can also combine the two conditional statements in one check
+				assert(speed &lt; 20, "speed = %f, but the speed limit is 20" % speed) # Show a message with clarifying details
 				[/codeblock]
 			</description>
 		</method>
diff --git a/modules/gdscript/gdscript_editor.cpp b/modules/gdscript/gdscript_editor.cpp
index 65c61cb57ca..e403b18ba19 100644
--- a/modules/gdscript/gdscript_editor.cpp
+++ b/modules/gdscript/gdscript_editor.cpp
@@ -430,6 +430,8 @@ void GDScriptLanguage::get_public_functions(List<MethodInfo> *p_functions) const
 		mi.name = "assert";
 		mi.return_val.type = Variant::NIL;
 		mi.arguments.push_back(PropertyInfo(Variant::BOOL, "condition"));
+		mi.arguments.push_back(PropertyInfo(Variant::STRING, "message"));
+		mi.default_arguments.push_back(String());
 		p_functions->push_back(mi);
 	}
 }