diff --git a/pkgs/development/compilers/nextpnr/default.nix b/pkgs/development/compilers/nextpnr/default.nix
index 3d1db7af2dd..dc8f750c567 100644
--- a/pkgs/development/compilers/nextpnr/default.nix
+++ b/pkgs/development/compilers/nextpnr/default.nix
@@ -50,7 +50,7 @@ with stdenv; mkDerivation rec {
       "-DBUILD_TESTS=ON"
       "-DICEBOX_ROOT=${icestorm}/share/icebox"
       "-DTRELLIS_INSTALL_PREFIX=${trellis}"
-      "-DPYTRELLIS_LIBDIR=${trellis}/lib/trellis"
+      "-DTRELLIS_LIBDIR=${trellis}/lib/trellis"
       "-DUSE_OPENMP=ON"
       # warning: high RAM usage
       "-DSERIALIZE_CHIPDB=OFF"