diff --git a/docs/users_guide/extending_ghc.rst b/docs/users_guide/extending_ghc.rst
index d89b51b87ccf20e7c951430b4033b1e309c63ca0..8eb56f3d370521c6053bb3ff7b645244f33fa8cd 100644
--- a/docs/users_guide/extending_ghc.rst
+++ b/docs/users_guide/extending_ghc.rst
@@ -594,7 +594,7 @@ is defined thus:
       , tcPluginStop    :: s -> TcPluginM ()
       }
 
-    type TcPluginSolver = EvBindsVar -> [Ct] -> [Ct] -> [Ct] -> TcPluginM TcPluginSolveResult
+    type TcPluginSolver = EvBindsVar -> [Ct] -> [Ct] -> TcPluginM TcPluginSolveResult
 
     type TcPluginRewriter = RewriteEnv -> [Ct] -> [Type] -> TcPluginM TcPluginRewriteResult