diff --git a/nixpkgs.nix b/nixpkgs.nix
index 99e50373..dd581a69 100644
--- a/nixpkgs.nix
+++ b/nixpkgs.nix
@@ -1,6 +1,6 @@
 let
-  rev = "e544ee88fa4590df75e221e645a03fe157a99e5b";
-  sha256 = "0j8pdr9ymk7a2p8pamcbq2rbhlcg923i6abdmdm6496973s5gb34";
+  rev = "c114cd459e1bac0d05e4e27c9ea43c99799cbbd1";
+  sha256 = "1hpspw8jbzq03k8a6izxnbqww42mihqaa6c8nszw30igiaqc98i2";
 in
 import (fetchTarball {
   inherit sha256;
diff --git a/shell.nix b/shell.nix
index 42c5bf4c..3f2f6317 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,4 +1,4 @@
-{pkgs ? import ./nixpkgs.nix { }, ghc ? pkgs.haskell.compiler.ghc8107}:
+{pkgs ? import ./nixpkgs.nix { }, ghc ? pkgs.haskell.compiler.ghc8104}:
 
 with pkgs;
 
diff --git a/stack.yaml b/stack.yaml
index 44242f96..13c33d06 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-18.16
+resolver: lts-18.6
 
 packages:
 - examples