diff --git a/overlays/musl.nix b/overlays/musl.nix
index 89dddc5093..3cd4770f94 100644
--- a/overlays/musl.nix
+++ b/overlays/musl.nix
@@ -25,10 +25,13 @@ final: prev: prev.lib.optionalAttrs prev.stdenv.hostPlatform.isMusl ({
   xz = prev.xz.override { enableStatic = true; };
   lzma = prev.lzma.override { enableStatic = true; };
   pcre = prev.pcre.overrideAttrs (_: { dontDisableStatic = true; });
-  secp256k1 = prev.secp256k1.overrideAttrs ( oldAttrs: {
-    configureFlags = oldAttrs.configureFlags ++ ["--enable-static"];  });
+  secp256k1 = prev.secp256k1.overrideAttrs (oldAttrs: {
+    configureFlags = oldAttrs.configureFlags ++ ["--enable-static"];
+  });
 
-  numactl = prev.numactl.overrideAttrs (_: { configureFlags = ["--enable-static"];});
+  numactl = prev.numactl.overrideAttrs (oldAttrs: {
+    configureFlags = (oldAttrs.configureFlags or []) ++ ["--enable-static"];
+  });
 
   # See https://github.com/input-output-hk/haskell.nix/issues/948
   postgresql = (prev.postgresql.overrideAttrs (_old: {