diff --git a/Cargo.lock b/Cargo.lock
index 0e6ffba..208e569 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -153,7 +153,8 @@ dependencies = [
 [[package]]
 name = "gmp-mpfr-sys"
 version = "1.4.7"
-source = "git+https://gitlab.com/tspiteri/gmp-mpfr-sys.git#21966f4bfb56c87d407eb14c72e92ef4e55856aa"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a146a7357ce9573bdcc416fc4a99b960e166e72d8eaffa7c59966d51866b5bfb"
 dependencies = [
  "libc",
  "winapi",
diff --git a/Cargo.toml b/Cargo.toml
index 3b2e286..ed4a5eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,3 @@
-[patch.crates-io]
-gmp-mpfr-sys = { git = "https://gitlab.com/tspiteri/gmp-mpfr-sys.git" }
-
 [workspace]
 members = ["kalk", "cli"]
 
diff --git a/flake.nix b/flake.nix
index eb8a100..87eff0b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -22,19 +22,15 @@
 
           src = self;
 
+          nativeBuildInputs = with final; [ gcc ];
+
           outputs = [ "out" "lib" ];
 
           postInstall = ''
             moveToOutput "lib" "$lib"
           '';
 
-          cargoLock = {
-            lockFile = self + "/Cargo.lock";
-            outputHashes = {
-              "gmp-mpfr-sys-1.4.7" =
-                "sha256-zHpGbEgh3MgAUVdlWrXq4Clj1boybi6DMOcsjgZbAh0=";
-            };
-          };
+          cargoLock = { lockFile = self + "/Cargo.lock"; };
 
           buildInputs = with final; [ gmp mpfr libmpc ];