diff --git a/src/libslic3r/GCode/WipeTower2.cpp b/src/libslic3r/GCode/WipeTower2.cpp
index 2e7c12f6ea..fed3f24b6c 100644
--- a/src/libslic3r/GCode/WipeTower2.cpp
+++ b/src/libslic3r/GCode/WipeTower2.cpp
@@ -2081,13 +2081,21 @@ WipeTower::ToolChangeResult WipeTower2::finish_layer()
     // brim with chamfer (gradual layer-by-layer reduction)
     int loops_num = (m_wipe_tower_brim_width + spacing / 2.f) / spacing;
 
-    // Apply chamfer reduction if feature is enabled and brim width is configured
-    if (m_wipe_tower_brim_width > 0 && m_prime_tower_brim_chamfer) {
-        if (!first_layer) {
+    // Apply brim logic based on chamfer setting
+    if (m_wipe_tower_brim_width > 0) {
+        if (first_layer) {
+            // First layer: always print full brim (loops_num unchanged)
+        } else if (m_prime_tower_brim_chamfer) {
+            // Non-first layer + chamfer enabled: apply gradual reduction
             // Calculate distance from first layer with tool changes
             size_t current_idx = m_layer_info - m_plan.begin();
             int    dist_to_1st = (int) current_idx - (int) m_first_layer_idx;
 
+            // Validate m_first_layer_idx to prevent invalid index access
+            if (m_first_layer_idx == size_t(-1) || m_first_layer_idx >= m_plan.size()) {
+                // Invalid first layer index, don't print brim
+                loops_num = 0;
+            } else {
             // Stop print chamfer if depth changes
             bool depth_changed = (m_layer_info->depth != m_plan[m_first_layer_idx].depth);
             if (depth_changed) {
@@ -2101,6 +2109,10 @@ WipeTower::ToolChangeResult WipeTower2::finish_layer()
                     loops_num = 0;
             }
         }
+        } else {
+            // Non-first layer + chamfer disabled: don't print brim (revert to original behavior)
+            loops_num = 0;
+        }
     }
 
     if (loops_num > 0) {