diff --git a/changelog/snippets/fix.6494.md b/changelog/snippets/fix.6494.md
new file mode 100644
index 0000000000..89b2cdbff1
--- /dev/null
+++ b/changelog/snippets/fix.6494.md
@@ -0,0 +1 @@
+- (#6494) Fix a crash when the `EnableDiskWatch` command line argument is enabled.
diff --git a/lua/system/blueprints-units.lua b/lua/system/blueprints-units.lua
index 8b311fb23a..0c9fd3bdd4 100644
--- a/lua/system/blueprints-units.lua
+++ b/lua/system/blueprints-units.lua
@@ -397,7 +397,7 @@ local function PostProcessUnit(unit)
         status.AllIntel = {}
         if intelBlueprint then
             for name, value in pairs(intelBlueprint) do
-    
+
                 -- may contain tables, such as `JamRadius`
                 if type(value) ~= 'table' then
                     if value == true or value > 0 then
@@ -555,7 +555,7 @@ local function PostProcessUnit(unit)
     -- Define a specific TransportSpeedReduction for all land and naval units.
     -- Experimentals have a TransportSpeedReduction of 1 due to transports gaining 1 speed and some survival maps loading experimentals into transports.
     -- Naval units also gain a TransportSpeedReduction of 1 to ensure mod compatibility.
-    if not unit.Physics.TransportSpeedReduction and not isStructure then    
+    if unit.Physics and not unit.Physics.TransportSpeedReduction and not isStructure then
         if isLand and isTech1 then
             unit.Physics.TransportSpeedReduction = 0.15
         elseif isLand and isTech2 then