diff --git a/flake.lock b/flake.lock
index e20a023..557626e 100644
--- a/flake.lock
+++ b/flake.lock
@@ -23,17 +23,16 @@
         "nixpkgs-unstable": "nixpkgs-unstable"
       },
       "locked": {
-        "lastModified": 1614746792,
-        "narHash": "sha256-KAxmQxYDRbB/pYW5vqvPSwZ3kft5UulZ5fY1nodP8FQ=",
+        "lastModified": 1617010607,
+        "narHash": "sha256-xaC+581n/gEI/NvtppOMWWD00I+O5ysVd17oEIHWo4w=",
         "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "43cb0fc8957be7ab027f8bd5d48bc22479032c1f",
+        "rev": "9ce7bf1e0276a9f71440ab6f74b044908647bcfc",
         "type": "github"
       },
       "original": {
         "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "43cb0fc8957be7ab027f8bd5d48bc22479032c1f",
         "type": "github"
       }
     },
@@ -103,17 +102,16 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1615307759,
-        "narHash": "sha256-KpzbA2Uf7ZSuu+Q7fAA1DBiY319HrU1QbjzsmgL3I8w=",
+        "lastModified": 1616785305,
+        "narHash": "sha256-Zgs4UrUZ2J6MJLTwO8AHHt9bPDyTdJLYyzgfdABKtF4=",
         "owner": "serokell",
         "repo": "nixpkgs",
-        "rev": "25cb6c920e31f80cc4c4559c840c5753d4a9012f",
+        "rev": "8addc8b778fbd9df4464ef0e8ac07d29ce7fcfa6",
         "type": "github"
       },
       "original": {
         "owner": "serokell",
         "repo": "nixpkgs",
-        "rev": "25cb6c920e31f80cc4c4559c840c5753d4a9012f",
         "type": "github"
       }
     },
diff --git a/flake.nix b/flake.nix
index a3c404f..c3a79fa 100644
--- a/flake.nix
+++ b/flake.nix
@@ -7,8 +7,8 @@
 
   inputs = {
     flake-utils.url = "github:numtide/flake-utils";
-    haskell-nix.url = "github:input-output-hk/haskell.nix/43cb0fc8957be7ab027f8bd5d48bc22479032c1f";
-    nixpkgs.url = "github:serokell/nixpkgs/25cb6c920e31f80cc4c4559c840c5753d4a9012f";
+    haskell-nix.url = "github:input-output-hk/haskell.nix";
+    nixpkgs.url = "github:serokell/nixpkgs";
   };
 
   outputs = { self, nixpkgs, flake-utils, haskell-nix }:
@@ -29,13 +29,13 @@
 
         checks =
           let
-            mkGhcCheck = ghcName: {
-              name = "test-${ghcName}";
-              value = check { ghc = pkgs.haskell-nix.compiler.${ghcName}; };
+            mkGhcCheck = ghcVersion: {
+              name = "test-ghc${ghcVersion}";
+              value = check { ghc = pkgs.haskell-nix.compiler."ghc${ghcVersion}"; };
             };
           in {
             test = with-utf8.checks.with-utf8-test;
-          } // lib.listToAttrs (map mkGhcCheck [ "ghc884" "ghc8104" ]);
+          } // lib.listToAttrs (map mkGhcCheck [ "884" "8104" "901" ]);
 
         apps.utf8-troubleshoot = {
           type = "app";
diff --git a/package.yaml b/package.yaml
index 1a82ab3..821ac8c 100644
--- a/package.yaml
+++ b/package.yaml
@@ -37,7 +37,7 @@ ghc-options:
   - -Wredundant-constraints
 
 dependencies:
-  - base >= 4.10 && < 4.15
+  - base >= 4.10 && < 4.16
   - text >= 0.7 && < 1.3
 
 library:
diff --git a/with-utf8.cabal b/with-utf8.cabal
index cf9aa22..36acf39 100644
--- a/with-utf8.cabal
+++ b/with-utf8.cabal
@@ -4,7 +4,7 @@ cabal-version: 1.18
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 82e6b04d01f14be8fc41ce3d7271039952fa94becdc1dd8d66d99b1fa434f675
+-- hash: f91b72904bb053decd8bf11fafaaaa6c44c48fb8f1b4046243127067afc269d3
 
 name:           with-utf8
 version:        1.0.2.2
@@ -50,7 +50,7 @@ library
       lib
   ghc-options: -Wall -Wcompat -Wincomplete-record-updates -Wincomplete-uni-patterns -Wredundant-constraints
   build-depends:
-      base >=4.10 && <4.15
+      base >=4.10 && <4.16
     , safe-exceptions >=0.1 && <0.2
     , text >=0.7 && <1.3
   default-language: Haskell2010
@@ -65,7 +65,7 @@ executable utf8-troubleshoot
   c-sources:
       app/utf8-troubleshoot/cbits/locale.c
   build-depends:
-      base >=4.10 && <4.15
+      base >=4.10 && <4.16
     , directory >=1.2.5.0 && <1.4
     , filepath >=1.0 && <1.5
     , process >=1.0.1.1 && <1.7
@@ -91,7 +91,7 @@ test-suite with-utf8-test
       tasty-discover:tasty-discover
   build-depends:
       HUnit
-    , base >=4.10 && <4.15
+    , base >=4.10 && <4.16
     , deepseq
     , hedgehog
     , safe-exceptions