diff --git a/src/layout.rs b/src/layout.rs
index 934e19d..27a152e 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -52,6 +52,26 @@ pub struct DungeonLayout {
     pub doors: Vec<Door>,
 }
 
+// Collect all room cells except those belonging to excluded room ids.
+pub fn blocked_room_cells(rooms: &[Room], excluded_room_ids: &[usize]) -> HashSet<(usize, usize)> {
+    let excluded: HashSet<usize> = excluded_room_ids.iter().copied().collect();
+    let mut blocked = HashSet::new();
+
+    for (room_idx, room) in rooms.iter().enumerate() {
+        if excluded.contains(&room_idx) {
+            continue;
+        }
+
+        for x in room.x..(room.x + room.width) {
+            for y in room.y..(room.y + room.height) {
+                blocked.insert((x, y));
+            }
+        }
+    }
+
+    blocked
+}
+
 // Build a layout based on settings and a derived deterministic seed.
 pub fn generate_layout(
     cols: usize,
@@ -178,9 +198,10 @@ pub fn generate_layout(
     for (start_room_id, end_room_id) in room_edges {
         let start = centers[start_room_id];
         let end = centers[end_room_id];
+        let blocked = blocked_room_cells(&rooms, &[start_room_id, end_room_id]);
 
         let path = if randomness <= 0.001 {
-            shortest_path_cells(start, end, cols, rows, &HashSet::new())
+            shortest_path_cells(start, end, cols, rows, &blocked)
         } else {
             Some(noisy_path(
                 start,
@@ -188,10 +209,11 @@ pub fn generate_layout(
                 cols,
                 rows,
                 randomness,
+                &blocked,
                 &mut path_rng,
             ))
         }
-        .or_else(|| shortest_path_cells(start, end, cols, rows, &HashSet::new()));
+        .or_else(|| shortest_path_cells(start, end, cols, rows, &blocked));
 
         if let Some(path) = path
             && path.len() >= 2
@@ -656,6 +678,7 @@ fn noisy_path(
     cols: usize,
     rows: usize,
     randomness: f32,
+    blocked: &HashSet<(usize, usize)>,
     rng: &mut SimpleRng,
 ) -> Vec<(usize, usize)> {
     if start == end {
@@ -698,6 +721,10 @@ fn noisy_path(
         let mut best_score = f32::INFINITY;
 
         for &candidate in &neighbors {
+            if blocked.contains(&candidate) && candidate != end {
+                continue;
+            }
+
             let step_dir = (
                 candidate.0 as isize - current.0 as isize,
                 candidate.1 as isize - current.1 as isize,
@@ -734,7 +761,7 @@ fn noisy_path(
     }
 
     if current != end
-        && let Some(tail) = shortest_path_cells(current, end, cols, rows, &HashSet::new())
+        && let Some(tail) = shortest_path_cells(current, end, cols, rows, blocked)
     {
         for &cell in tail.iter().skip(1) {
             path.push(cell);
diff --git a/src/main.rs b/src/main.rs
index 06b6d19..7ba61d7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,7 +10,9 @@ use std::thread;
 
 use eframe::egui;
 use egui::{Color32, Stroke};
-use layout::{DoorSettings, DungeonLayout, corridor_cells, shortest_path_cells};
+use layout::{
+    DoorSettings, DungeonLayout, blocked_room_cells, corridor_cells, shortest_path_cells,
+};
 use ui::{AddTool, UiSettings, draw_side_panel};
 
 // Boot the native app and start the egui event loop.
@@ -333,7 +335,6 @@ impl DungeonApp {
 
     // Recalculate corridor paths connected to a moved room.
     fn reroute_corridors_for_room(&mut self, room_idx: usize) {
-        let empty = HashSet::new();
         for corridor in &mut self.layout.corridors {
             if corridor.start_room_id != room_idx && corridor.end_room_id != room_idx {
                 continue;
@@ -341,9 +342,15 @@ impl DungeonApp {
 
             let start = self.layout.rooms[corridor.start_room_id].center_cell();
             let end = self.layout.rooms[corridor.end_room_id].center_cell();
-            corridor.path =
-                shortest_path_cells(start, end, self.settings.cols, self.settings.rows, &empty)
-                    .unwrap_or_else(|| vec![start, end]);
+            let blocked = blocked_room_cells(
+                &self.layout.rooms,
+                &[corridor.start_room_id, corridor.end_room_id],
+            );
+            if let Some(path) =
+                shortest_path_cells(start, end, self.settings.cols, self.settings.rows, &blocked)
+            {
+                corridor.path = path;
+            }
         }
     }
 
@@ -383,6 +390,7 @@ impl DungeonApp {
             self.drag_state = None;
             return;
         }
+        let corridor = &self.layout.corridors[drag.corridor_index];
 
         let target = (
             (grid_x.floor().max(0.0) as usize).min(self.settings.cols.saturating_sub(1)),
@@ -395,6 +403,10 @@ impl DungeonApp {
             target,
             self.settings.cols,
             self.settings.rows,
+            &blocked_room_cells(
+                &self.layout.rooms,
+                &[corridor.start_room_id, corridor.end_room_id],
+            ),
         ) else {
             return;
         };
@@ -540,16 +552,7 @@ impl DungeonApp {
             return;
         };
 
-        let mut blocked = HashSet::new();
-        for room in &self.layout.rooms {
-            for x in room.x..(room.x + room.width) {
-                for y in room.y..(room.y + room.height) {
-                    blocked.insert((x, y));
-                }
-            }
-        }
-        blocked.remove(&start);
-        blocked.remove(&end);
+        let blocked = blocked_room_cells(&self.layout.rooms, &[start_room, end_room]);
 
         let Some(path) =
             shortest_path_cells(start, end, self.settings.cols, self.settings.rows, &blocked)
@@ -1604,13 +1607,14 @@ fn reroute_path_through_cell(
     target_cell: (usize, usize),
     cols: usize,
     rows: usize,
+    blocked_room_cells_set: &HashSet<(usize, usize)>,
 ) -> Option<Vec<(usize, usize)>> {
     let (&start, &end) = (original_path.first()?, original_path.last()?);
     if start == end {
         return None;
     }
 
-    let mut blocked = HashSet::new();
+    let mut blocked = blocked_room_cells_set.clone();
     blocked.insert(original_cell);
     blocked.remove(&start);
     blocked.remove(&end);