diff --git a/lib/generate.js b/lib/generate.js
index e0bd2c7b..148e0279 100644
--- a/lib/generate.js
+++ b/lib/generate.js
@@ -209,7 +209,7 @@
         output += "interface NearleyRule {\n";
         output += "  name: string;\n";
         output += "  symbols: NearleySymbol[];\n";
-        output += "  postprocess?: (d: any[], loc?: number, reject?: {}) => any;\n";
+        output += "  postprocess?: (d: any, loc?: number, reject?: {}) => any;\n";
         output += "};\n";
         output += "\n";
         output += "type NearleySymbol = string | { literal: any } | { test: (token: any) => boolean };\n";