diff --git a/core/avisynth.h b/core/avisynth.h
index d64154f7c..b1e68deb4 100644
--- a/core/avisynth.h
+++ b/core/avisynth.h
@@ -39,7 +39,7 @@
 #ifndef __AVISYNTH_H__
 #define __AVISYNTH_H__
 
-enum { AVISYNTH_INTERFACE_VERSION = 2 };
+enum { AVISYNTH_INTERFACE_VERSION = 3 };
 
 
 /* Define all types necessary for interfacing with avisynth.dll
diff --git a/core/avisynth_wrap.cpp b/core/avisynth_wrap.cpp
index e3f0b967c..e0b52e97c 100644
--- a/core/avisynth_wrap.cpp
+++ b/core/avisynth_wrap.cpp
@@ -60,16 +60,15 @@ AviSynthWrapper::AviSynthWrapper() {
 		if (CreateScriptEnv == NULL)
 			throw _T("Failed to get function from avisynth.dll");
 
-		env = CreateScriptEnv(AVISYNTH_INTERFACE_VERSION);
+		// Require Avisynth 2.5.6+?
+		if (Options.AsBool(_T("Allow Ancient Avisynth")))
+			env = CreateScriptEnv(AVISYNTH_INTERFACE_VERSION-1);
+		else
+			env = CreateScriptEnv(AVISYNTH_INTERFACE_VERSION);
 
 		if (env == NULL)
 			throw _T("Failed to create a new avisynth script environment. Avisynth is too old?");
 
-		// Check for a new enough avisynth version by looking for the most obscure function used
-		// fix me, no longer useful with "Cache"?
-		if (!env->FunctionExists("Cache"))
-			throw _T("Installed version of avisynth is too old");
-
 		// Set memory limit
 		int memoryMax = Options.AsInt(_T("Avisynth MemoryMax"));
 		if (memoryMax != 0)