diff --git a/mmseg/models/backbones/ddrnet.py b/mmseg/models/backbones/ddrnet.py
index 4508aade82..4b7a3d13fc 100644
--- a/mmseg/models/backbones/ddrnet.py
+++ b/mmseg/models/backbones/ddrnet.py
@@ -180,11 +180,14 @@ def _make_layer(self, block, inplanes, planes, num_blocks, stride=1):
 
     def forward(self, x):
         """Forward function."""
-        out_size = (x.shape[-2] // 8, x.shape[-1] // 8)
 
         # stage 0-2
         x = self.stem(x)
 
+        # Use actual spatial dims after stem to avoid off-by-one errors
+        # when input resolution is not perfectly divisible by 8.
+        out_size = x.shape[-2:]
+
         # stage3
         x_c = self.context_branch_layers[0](x)
         x_s = self.spatial_branch_layers[0](x)