diff --git a/src/layout/floating.rs b/src/layout/floating.rs
index 3fac30f22b..d3d0395a63 100644
--- a/src/layout/floating.rs
+++ b/src/layout/floating.rs
@@ -783,6 +783,18 @@ impl<W: LayoutElement> FloatingSpace<W> {
         let win_height = ensure_min_max_size(win_height, min_size.h, max_size.h);
 
         let win_size = Size::from((win_width, win_height));
+        if win_size.w > 0
+            && win_size.h > 0
+            && win.size() == win_size
+            && win.sizing_mode().is_normal()
+            && win.pending_sizing_mode().is_normal()
+            && matches!(
+                win.configure_intent(),
+                ConfigureIntent::NotNeeded | ConfigureIntent::Throttled
+            )
+        {
+            return;
+        }
         win.request_size_once(win_size, animate);
     }
 
@@ -830,6 +842,18 @@ impl<W: LayoutElement> FloatingSpace<W> {
         let win_width = ensure_min_max_size(win_width, min_size.w, max_size.w);
 
         let win_size = Size::from((win_width, win_height));
+        if win_size.w > 0
+            && win_size.h > 0
+            && win.size() == win_size
+            && win.sizing_mode().is_normal()
+            && win.pending_sizing_mode().is_normal()
+            && matches!(
+                win.configure_intent(),
+                ConfigureIntent::NotNeeded | ConfigureIntent::Throttled
+            )
+        {
+            return;
+        }
         win.request_size_once(win_size, animate);
     }
 
diff --git a/src/tests/floating.rs b/src/tests/floating.rs
index 3ceedfd4f2..726d0c90ea 100644
--- a/src/tests/floating.rs
+++ b/src/tests/floating.rs
@@ -215,13 +215,9 @@ fn resize_to_same_size() {
 
     // This needn't request anything because we're already that size; the size in the current
     // server state matches the requested size.
-    //
-    // FIXME: However, currently it will request the size anyway because the code checks the
-    // current server state, and the last size niri requested of the window was 100×100 (even if
-    // the window already acked and committed in response).
     assert_snapshot!(
         f.client(id).window(&surface).format_recent_configures(),
-        @"size: 200 × 200, bounds: 1920 × 1080, states: [Activated]"
+        @""
     );
 }
 
@@ -1357,10 +1353,8 @@ fn repeated_size_request() {
     f.double_roundtrip(id);
 
     // This should send a new configure since the window had committed.
-    //
-    // FIXME: doesn't request that currently.
     assert_snapshot!(
         f.client(id).window(&surface).format_recent_configures(),
-        @""
+        @"size: 200 × 100, bounds: 1920 × 1080, states: [Activated]"
     );
 }
diff --git a/src/window/mapped.rs b/src/window/mapped.rs
index e951e3324d..9334f9f85f 100644
--- a/src/window/mapped.rs
+++ b/src/window/mapped.rs
@@ -800,6 +800,13 @@ impl LayoutElement for Mapped {
             self.animate_next_configure = true;
         }
 
+        // If we requested a concrete size before and the client committed without applying it,
+        // role state may already contain that size even though the actual window size differs.
+        // In that case, force another configure on the next same-size request.
+        if !changed && size.w > 0 && size.h > 0 && self.window.geometry().size != size {
+            self.needs_configure = true;
+        }
+
         self.request_size_once = Some(RequestSizeOnce::WaitingForConfigure);
     }