diff --git a/pkgs/development/interpreters/octave/default.nix b/pkgs/development/interpreters/octave/default.nix
index 71421c6e5eea..a1add4055af5 100644
--- a/pkgs/development/interpreters/octave/default.nix
+++ b/pkgs/development/interpreters/octave/default.nix
@@ -171,11 +171,15 @@ stdenv.mkDerivation (finalAttrs: {
 
   enableParallelBuilding = true;
 
-  # Fix linker error on Darwin (see https://trac.macports.org/ticket/61865)
-  NIX_LDFLAGS = lib.optionalString stdenv.hostPlatform.isDarwin "-lobjc";
-
-  # See https://savannah.gnu.org/bugs/?50339
-  F77_INTEGER_8_FLAG = lib.optionalString use64BitIdx "-fdefault-integer-8";
+  env =
+    lib.optionalAttrs stdenv.hostPlatform.isDarwin {
+      # Fix linker error on Darwin (see https://trac.macports.org/ticket/61865)
+      NIX_LDFLAGS = "-lobjc";
+    }
+    // lib.optionalAttrs use64BitIdx {
+      # See https://savannah.gnu.org/bugs/?50339
+      F77_INTEGER_8_FLAG = "-fdefault-integer-8";
+    };
 
   configureFlags = [
     "--with-blas=blas"