diff --git a/flake.lock b/flake.lock
index c39e6a9732..7696551e2c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1692404241,
-        "narHash": "sha256-TRZlFHtrQI6Kh8RFqnjBF2uNNi/c66ldB4WuIcrwMzg=",
+        "lastModified": 1700014976,
+        "narHash": "sha256-dSGpS2YeJrXW5aH9y7Abd235gGufY3RuZFth6vuyVtU=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "2f9286912cb215969ece465147badf6d07aa43fe",
+        "rev": "592047fc9e4f7b74a4dc85d1b9f5243dfe4899e3",
         "type": "github"
       },
       "original": {
@@ -33,11 +33,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1692410823,
-        "narHash": "sha256-YM1QCenpghNqgleUmoCJUArTuMEBqScyQuhepA6JZaI=",
+        "lastModified": 1700084394,
+        "narHash": "sha256-ZPvcR/TBpKTDXtjVfuQP3ntHnRl1ZX8DUYJX+/qTzcc=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "598b2f04ed252eb5808b108d7a10084c0c548753",
+        "rev": "c1125ef3963884cc5bc534ba752baaf2af835dac",
         "type": "github"
       },
       "original": {
@@ -66,11 +66,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1689068808,
-        "narHash": "sha256-6ixXo3wt24N/melDWjq70UuHQLxGV8jZvooRanIHXw0=",
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "919d646de7be200f3bf08cb76ae1f09402b6f9b4",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 98b43f4c61..882baa3b69 100644
--- a/flake.nix
+++ b/flake.nix
@@ -89,7 +89,7 @@
           buildInputs = [
             rustVersion
             openssl
-            pkgconfig
+            pkg-config
 
             git
             stdenv.cc.cc.lib
diff --git a/src/core/src/ffi/signature.rs b/src/core/src/ffi/signature.rs
index 825e091f4d..06a0bd9fe5 100644
--- a/src/core/src/ffi/signature.rs
+++ b/src/core/src/ffi/signature.rs
@@ -167,7 +167,7 @@ ffi_fn! {
 unsafe fn signature_first_mh(ptr: *const SourmashSignature) -> Result<*mut SourmashKmerMinHash> {
     let sig = SourmashSignature::as_rust(ptr);
 
-    match sig.signatures.get(0) {
+    match sig.signatures.first() {
         Some(Sketch::MinHash(mh)) => {
             Ok(SourmashKmerMinHash::from_rust(mh.clone()))
         },