diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 86a89fd6f2..ba391ab63f 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -2343,7 +2343,7 @@ std::string GCode::extrude_loop(ExtrusionLoop loop, std::string description, dou
         const EdgeGrid::Grid* edge_grid_ptr = (lower_layer_edge_grid && *lower_layer_edge_grid)
                                                 ? lower_layer_edge_grid->get()
                                                 : nullptr;
-        Point seam = m_seam_placer.get_seam(m_layer->id(), seam_position, loop,
+        Point seam = m_seam_placer.get_seam(*m_layer, seam_position, loop,
                          last_pos, EXTRUDER_CONFIG(nozzle_diameter),
                          (m_layer == NULL ? nullptr : m_layer->object()),
                          was_clockwise, edge_grid_ptr);
diff --git a/src/libslic3r/GCode/SeamPlacer.cpp b/src/libslic3r/GCode/SeamPlacer.cpp
index ff01621b8a..243b633fce 100644
--- a/src/libslic3r/GCode/SeamPlacer.cpp
+++ b/src/libslic3r/GCode/SeamPlacer.cpp
@@ -6,6 +6,7 @@
 #include "libslic3r/EdgeGrid.hpp"
 #include "libslic3r/ClipperUtils.hpp"
 #include "libslic3r/SVG.hpp"
+#include "libslic3r/Layer.hpp"
 
 namespace Slic3r {
 
@@ -282,7 +283,7 @@ void SeamPlacer::init(const Print& print)
 
 
 
-Point SeamPlacer::get_seam(const size_t layer_idx, const SeamPosition seam_position,
+Point SeamPlacer::get_seam(const Layer& layer, const SeamPosition seam_position,
                const ExtrusionLoop& loop, Point last_pos, coordf_t nozzle_dmr,
                const PrintObject* po, bool was_clockwise, const EdgeGrid::Grid* lower_layer_edge_grid)
 {
@@ -292,6 +293,25 @@ Point SeamPlacer::get_seam(const size_t layer_idx, const SeamPosition seam_posit
 
     size_t po_idx = std::find(m_po_list.begin(), m_po_list.end(), po) - m_po_list.begin();
 
+    // Find current layer in respective PrintObject. Cache the result so the
+    // lookup is only done once per layer, not for each loop.
+    const Layer* layer_po = nullptr;
+    if (po == m_last_po && layer.print_z == m_last_print_z)
+        layer_po = m_last_layer_po;
+    else {
+        layer_po = po->get_layer_at_printz(layer.print_z);
+        m_last_po = po;
+        m_last_print_z = layer.print_z;
+        m_last_layer_po = layer_po;
+    }
+    if (! layer_po)
+        return last_pos;
+
+    // Index of this layer in the respective PrintObject.
+    size_t layer_idx = layer_po->id() - po->layers().front()->id(); // raft layers
+
+    assert(layer_idx < po->layer_count());
+
     if (this->is_custom_seam_on_layer(layer_idx, po_idx)) {
         // Seam enf/blockers can begin and end in between the original vertices.
         // Let add extra points in between and update the leghths.
diff --git a/src/libslic3r/GCode/SeamPlacer.hpp b/src/libslic3r/GCode/SeamPlacer.hpp
index 28ab913134..759e1592eb 100644
--- a/src/libslic3r/GCode/SeamPlacer.hpp
+++ b/src/libslic3r/GCode/SeamPlacer.hpp
@@ -13,6 +13,7 @@ namespace Slic3r {
 class PrintObject;
 class ExtrusionLoop;
 class Print;
+class Layer;
 namespace EdgeGrid { class Grid; }
 
 
@@ -40,7 +41,7 @@ class SeamPlacer {
 public:
     void init(const Print& print);
 
-    Point get_seam(const size_t layer_idx, const SeamPosition seam_position,
+    Point get_seam(const Layer& layer, const SeamPosition seam_position,
                    const ExtrusionLoop& loop, Point last_pos,
                    coordf_t nozzle_diameter, const PrintObject* po,
                    bool was_clockwise, const EdgeGrid::Grid* lower_layer_edge_grid);
@@ -55,6 +56,11 @@ private:
         TreeType tree;
     };
 
+    // Just a cache to save some lookups.
+    const Layer* m_last_layer_po = nullptr;
+    coordf_t m_last_print_z = -1.;
+    const PrintObject* m_last_po = nullptr;
+
 
     std::vector<std::vector<CustomTrianglesPerLayer>> m_enforcers;
     std::vector<std::vector<CustomTrianglesPerLayer>> m_blockers;