diff --git a/src/common/scripting/interface/vmnatives.cpp b/src/common/scripting/interface/vmnatives.cpp
index 096722e76d..1df737d165 100644
--- a/src/common/scripting/interface/vmnatives.cpp
+++ b/src/common/scripting/interface/vmnatives.cpp
@@ -848,6 +848,13 @@ DEFINE_ACTION_FUNCTION(_Wads, ReadLump)
 	ACTION_RETURN_STRING(isLumpValid ? GetStringFromLump(lump, false) : FString());
 }
 
+DEFINE_ACTION_FUNCTION(_Wads, GetLumpLength)
+{
+	PARAM_PROLOGUE;
+	PARAM_INT(lump);
+	ACTION_RETURN_INT(fileSystem.FileLength(lump));
+}
+
 //==========================================================================
 //
 // CVARs
diff --git a/wadsrc/static/zscript/engine/base.zs b/wadsrc/static/zscript/engine/base.zs
index c0754f7054..2644dc197d 100644
--- a/wadsrc/static/zscript/engine/base.zs
+++ b/wadsrc/static/zscript/engine/base.zs
@@ -862,6 +862,7 @@ struct Wads	// todo: make FileSystem an alias to 'Wads'
 	native static int FindLump(string name, int startlump = 0, FindLumpNamespace ns = GlobalNamespace);
 	native static int FindLumpFullName(string name, int startlump = 0, bool noext = false);
 	native static string ReadLump(int lump);
+	native static int GetLumpLength(int lump);
 
 	native static int GetNumLumps();
 	native static string GetLumpName(int lump);