diff --git a/csound-expression.cabal b/csound-expression.cabal
--- a/csound-expression.cabal
+++ b/csound-expression.cabal
@@ -1,5 +1,5 @@
 Name:          csound-expression
-Version:       5.3.0
+Version:       5.3.1
 Cabal-Version: >= 1.6
 License:       BSD3
 License-file:  LICENSE
@@ -79,7 +79,7 @@
   Ghc-Options:    -Wall
   Build-Depends:
         base >= 4, base < 5, process, data-default, Boolean >= 0.1.0, colour >= 2.0, transformers >= 0.3, containers,
-        csound-expression-typed >= 0.2.0.2, csound-expression-dynamic >= 0.3.2, temporal-media >= 0.6.1,
+        csound-expression-typed >= 0.2.1.0, csound-expression-dynamic >= 0.3.2, temporal-media >= 0.6.1,
         csound-expression-opcodes >= 0.0.4.0
   Hs-Source-Dirs:      src/
   Exposed-Modules:
diff --git a/src/Csound/Air/Filter.hs b/src/Csound/Air/Filter.hs
--- a/src/Csound/Air/Filter.hs
+++ b/src/Csound/Air/Filter.hs
@@ -561,8 +561,8 @@
 zdf2 :: Sig -> Sig -> Sig -> (Sig, Sig, Sig)
 zdf2 cfq q asig = zdf_2pole_mode asig cfq (uon 0.5 25 q)
 
-zpole2 :: D -> Sig -> Sig -> Sig -> Sig
-zpole2 n cfq q asig = zdf_2pole asig cfq (uon 0.5 25 q) `withSig` 0
+zpole2 :: Sig -> Sig -> Sig -> Sig -> Sig
+zpole2 n cfq q asig = zdf_2pole asig cfq (uon 0.5 25 q) `withSig` n
 
 -- | zero delay feedback 2 pole Low pass filter. Q is unipolar [0, 1]
 --