diff --git a/checks/autoescalate/default.nix b/checks/autoescalate/default.nix
index da90eda..65cc372 100644
--- a/checks/autoescalate/default.nix
+++ b/checks/autoescalate/default.nix
@@ -35,12 +35,20 @@ nixosTest {
     };
 
   testScript = ''
-    # Set up loop devices
-    machine.succeed('dd if=/dev/zero of=/tmp/blockfile bs=1M count=1')
-    machine.succeed('dd if=/dev/urandom of=/tmp/input.iso bs=100K count=1')
-    machine.succeed('losetup /dev/loop0 /tmp/blockfile')
+    ${builtins.readFile ../common.py}
 
-    with subtest("should succeed when run as non-root wheel user"):
-        machine.succeed('timeout 10 su admin -c "caligula burn /tmp/input.iso --force -o /dev/loop0 --hash skip --compression auto --root always --interactive never"')
+    try:
+        # Set up loop devices
+        machine.succeed('dd if=/dev/zero of=/tmp/blockfile bs=1M count=1')
+        machine.succeed('dd if=/dev/urandom of=/tmp/input.iso bs=100K count=1')
+        machine.succeed('losetup /dev/loop0 /tmp/blockfile')
+
+        # Sanity check: can we run something without asking for a password?
+        machine.succeed('timeout 10 su admin -c "${escalationTool} -- echo We are able to escalate without asking for a password"')
+
+        with subtest("should succeed when run as non-root wheel user"):
+            machine.succeed('timeout 10 su admin -c "caligula burn /tmp/input.iso --force -o /dev/loop0 --hash skip --compression auto --root always --interactive never"')
+    finally: 
+        print_logs(machine)
   '';
 }
diff --git a/checks/blocksize.nix b/checks/blocksize.nix
new file mode 100644
index 0000000..80c9aa2
--- /dev/null
+++ b/checks/blocksize.nix
@@ -0,0 +1,62 @@
+{ lib, nixosTest, imageSize, blockSize, diskSizeMiB }:
+let
+  serial = "awawawawawa";
+  diskFile = "/tmp/block-file.img";
+  byDiskPath = "/dev/disk/by-id/usb-QEMU_QEMU_HARDDISK_${serial}-0:0";
+in nixosTest {
+  name = "blocksize-bs${toString blockSize}-image${toString imageSize}-diskMiB${
+      toString diskSizeMiB
+    }";
+
+  nodes.machine = { pkgs, lib, ... }:
+    with lib; {
+      imports = [ ];
+
+      users.users = {
+        admin = {
+          isNormalUser = true;
+          extraGroups = [ "wheel" ];
+        };
+      };
+
+      environment.systemPackages = with pkgs; [ caligula ];
+      virtualisation.qemu.options =
+        [ "-drive" "if=none,id=usbstick,format=raw,file=${diskFile}" ]
+        ++ [ "-usb" ] ++ [ "-device" "usb-ehci,id=ehci" ] ++ [
+          "-device"
+          "usb-storage,bus=ehci.0,drive=usbstick,serial=${serial},physical_block_size=${
+            toString blockSize
+          }"
+        ];
+    };
+
+  testScript = with lib; ''
+    import os
+
+    print("Creating file image at ${diskFile}")
+    os.system("dd bs=1M count=${
+      toString diskSizeMiB
+    } if=/dev/urandom of=${diskFile}")
+
+    ${readFile ./common.py}
+
+    machine.start()
+    machine.wait_for_unit('default.target')
+    print(machine.execute('stat $(readlink -f ${byDiskPath})', check_output=True)[1])
+    try:
+        machine.succeed('dd if=/dev/urandom of=/tmp/input.iso bs=1 count=${
+          toString imageSize
+        }')
+        with subtest("executes successfully"):
+            machine.succeed('caligula burn /tmp/input.iso --force -o $(readlink -f ${byDiskPath}) --hash skip --compression auto --interactive never')
+
+        with subtest("burns correctly"):
+            machine.succeed('dd if=${byDiskPath} of=/tmp/written.iso bs=1 count=${
+              toString imageSize
+            }')
+            machine.succeed('diff -s /tmp/input.iso /tmp/written.iso')
+        
+    finally: 
+        print_logs(machine)
+  '';
+}
diff --git a/checks/common.py b/checks/common.py
new file mode 100644
index 0000000..84b0309
--- /dev/null
+++ b/checks/common.py
@@ -0,0 +1,6 @@
+def print_logs(machine):
+    _, output = machine.execute(
+        'for x in $(find /tmp/caligula-* -type f); do echo "$x"; cat "$x"; echo; done',
+        check_output=True,
+    )
+    print(output)
diff --git a/checks/default.nix b/checks/default.nix
index 51e76d4..07b1654 100644
--- a/checks/default.nix
+++ b/checks/default.nix
@@ -5,15 +5,34 @@ let
     inherit system;
     overlays = [ self.overlays.default ];
   };
-in {
+  lib = pkgs.lib;
+in with lib;
+{
   headless = pkgs.callPackage ./headless { };
   smoke-test-simple = pkgs.callPackage ./smoke-test-simple { };
 } //
 
-(if system == "x86_64-linux" then {
-  autoescalate-doas =
-    pkgs.callPackage ./autoescalate { escalationTool = "doas"; };
-  autoescalate-sudo =
-    pkgs.callPackage ./autoescalate { escalationTool = "sudo"; };
-} else
+(if system == "x86_64-linux" then
+  {
+    autoescalate-doas =
+      pkgs.callPackage ./autoescalate { escalationTool = "doas"; };
+    autoescalate-sudo =
+      pkgs.callPackage ./autoescalate { escalationTool = "sudo"; };
+  } //
+
+  # blocksize alignment tests
+  (let
+    MiB = 1048576;
+    parameters = cartesianProduct {
+      blockSize = [ 512 1024 2048 4096 8192 ];
+      imageSize = [ (10 * MiB) (10 * MiB + 51) ];
+    };
+  in listToAttrs (map ({ imageSize, blockSize }: rec {
+    name = value.name;
+    value = pkgs.callPackage ./blocksize.nix {
+      inherit lib blockSize imageSize;
+      diskSizeMiB = 64;
+    };
+  }) parameters))
+else
   { })
diff --git a/checks/headless/default.nix b/checks/headless/default.nix
index 674b64c..3f358d4 100644
--- a/checks/headless/default.nix
+++ b/checks/headless/default.nix
@@ -1,7 +1,8 @@
 { lib, caligula, runCommand }:
 runCommand "caligula-headless-test" {
   buildInputs = [ caligula ];
-  isoInnerHash = "3972dc9744f6499f0f9b2dbf76696f2ae7ad8af9b23dde66d6af86c9dfb36986";
+  isoInnerHash =
+    "3972dc9744f6499f0f9b2dbf76696f2ae7ad8af9b23dde66d6af86c9dfb36986";
   meta.timeout = 10;
 } ''
   caligula burn ${./input.iso.gz} \
@@ -11,11 +12,7 @@ runCommand "caligula-headless-test" {
     --hash-of raw \
     --compression auto 
 
-  for x in $(find /tmp/caligula-* -type f); do
-    echo "$x"
-    cat "$x"
-    echo
-  done
+  diff ${./expected.iso} ./out.iso
 
-  diff ${./expected.iso} ./out.iso && (echo 1 > $out)
+  echo 1 > $out
 ''