diff --git a/nixos/modules/installer/tools/nixos-generate-config.pl b/nixos/modules/installer/tools/nixos-generate-config.pl
index 97a30634dc7e..926d1e3133f7 100644
--- a/nixos/modules/installer/tools/nixos-generate-config.pl
+++ b/nixos/modules/installer/tools/nixos-generate-config.pl
@@ -402,7 +402,7 @@ EOF
         if ($status != 0 || join("", @info) =~ /ERROR:/) {
             die "Failed to retrieve subvolume info for $mountPoint\n";
         }
-        my @ids = join("", @info) =~ m/Subvolume ID:[ \t\n]*([0-9]*)/;
+        my @ids = join("\n", @info) =~ m/^(?!\/\n).*Subvolume ID:[ \t\n]*([0-9]+)/s;
         if ($#ids > 0) {
             die "Btrfs subvol name for $mountPoint listed multiple times in mount\n"
         } elsif ($#ids == 0) {
diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index 82b5bcda9217..cc03e54ead63 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -197,7 +197,7 @@ sub GrubFs {
                 if ($status != 0) {
                     die "Failed to retrieve subvolume info for @{[$fs->mount]}\n";
                 }
-                my @ids = join("", @id_info) =~ m/Subvolume ID:[ \t\n]*([^ \t\n]*)/;
+                my @ids = join("\n", @id_info) =~ m/^(?!\/\n).*Subvolume ID:[ \t\n]*([0-9]+)/s;
                 if ($#ids > 0) {
                     die "Btrfs subvol name for @{[$fs->device]} listed multiple times in mount\n"
                 } elsif ($#ids == 0) {