diff --git a/maintainers/scripts/nix-generate-from-cpan.pl b/maintainers/scripts/nix-generate-from-cpan.pl
index 942cba792ef..2dda39fd12e 100755
--- a/maintainers/scripts/nix-generate-from-cpan.pl
+++ b/maintainers/scripts/nix-generate-from-cpan.pl
@@ -395,15 +395,20 @@ my $meta = read_meta($pkg_path);
 
 DEBUG( "metadata: ", encode_json( $meta->as_struct ) ) if defined $meta;
 
+my @runtime_deps = sort( uniq( get_deps( $cb, $meta, "runtime" ) ) );
+INFO("runtime deps: @runtime_deps");
+
 my @build_deps = sort( uniq(
         get_deps( $cb, $meta, "configure" ),
         get_deps( $cb, $meta, "build" ),
         get_deps( $cb, $meta, "test" )
 ) );
-INFO("build deps: @build_deps");
 
-my @runtime_deps = sort( uniq( get_deps( $cb, $meta, "runtime" ) ) );
-INFO("runtime deps: @runtime_deps");
+# Filter out runtime dependencies since those are already handled.
+my %in_runtime_deps = map { $_ => 1 } @runtime_deps;
+@build_deps = grep { not $in_runtime_deps{$_} } @build_deps;
+
+INFO("build deps: @build_deps");
 
 my $homepage = $meta ? $meta->resources->{homepage} : undef;
 INFO("homepage: $homepage") if defined $homepage;