diff --git a/xs/src/TriangleMesh.cpp b/xs/src/TriangleMesh.cpp
index 246d94a6d..dcdf75807 100644
--- a/xs/src/TriangleMesh.cpp
+++ b/xs/src/TriangleMesh.cpp
@@ -165,7 +165,7 @@ void TriangleMesh::rotate(double angle, Point* center)
 }
 
 void
-TriangleMesh::slice(const std::vector<double> &z, std::vector<Polygons>* layers)
+TriangleMesh::slice(const std::vector<float> &z, std::vector<Polygons>* layers)
 {
     /*
        This method gets called with a list of unscaled Z coordinates and outputs
@@ -190,6 +190,9 @@ TriangleMesh::slice(const std::vector<double> &z, std::vector<Polygons>* layers)
         At the end, we free the tables generated by analyze() as we don't 
         need them anymore.
         FUTURE: parallelize slice_facet() and make_loops()
+        
+        NOTE: this method accepts a vector of floats because the mesh coordinate
+        type is float.
     */
     
     // build a table to map a facet_idx to its three edge indices
@@ -256,8 +259,8 @@ TriangleMesh::slice(const std::vector<double> &z, std::vector<Polygons>* layers)
         stl_facet* facet = &this->stl.facet_start[facet_idx];
         
         // find facet extents
-        double min_z = fminf(facet->vertex[0].z, fminf(facet->vertex[1].z, facet->vertex[2].z));
-        double max_z = fmaxf(facet->vertex[0].z, fmaxf(facet->vertex[1].z, facet->vertex[2].z));
+        float min_z = fminf(facet->vertex[0].z, fminf(facet->vertex[1].z, facet->vertex[2].z));
+        float max_z = fmaxf(facet->vertex[0].z, fmaxf(facet->vertex[1].z, facet->vertex[2].z));
         
         #ifdef SLIC3R_DEBUG
         printf("\n==> FACET %d (%f,%f,%f - %f,%f,%f - %f,%f,%f):\n", facet_idx,
@@ -275,16 +278,16 @@ TriangleMesh::slice(const std::vector<double> &z, std::vector<Polygons>* layers)
         }
         
         // find layer extents
-        std::vector<double>::const_iterator min_layer, max_layer;
-        min_layer = std::lower_bound(z.begin(), z.end(), min_z - EPSILON); // first layer whose slice_z is >= min_z
-        max_layer = std::upper_bound(z.begin() + (min_layer - z.begin()), z.end(), max_z + EPSILON) - 1; // last layer whose slice_z is <= max_z
+        std::vector<float>::const_iterator min_layer, max_layer;
+        min_layer = std::lower_bound(z.begin(), z.end(), min_z); // first layer whose slice_z is >= min_z
+        max_layer = std::upper_bound(z.begin() + (min_layer - z.begin()), z.end(), max_z) - 1; // last layer whose slice_z is <= max_z
         #ifdef SLIC3R_DEBUG
         printf("layers: min = %d, max = %d\n", (int)(min_layer - z.begin()), (int)(max_layer - z.begin()));
         #endif
         
-        for (std::vector<double>::const_iterator it = min_layer; it != max_layer + 1; ++it) {
-            std::vector<double>::size_type layer_idx = it - z.begin();
-            double slice_z = *it / SCALING_FACTOR;
+        for (std::vector<float>::const_iterator it = min_layer; it != max_layer + 1; ++it) {
+            std::vector<float>::size_type layer_idx = it - z.begin();
+            float slice_z = *it / SCALING_FACTOR;
             std::vector<IntersectionPoint> points;
             std::vector< std::vector<IntersectionPoint>::size_type > points_on_layer;
             bool found_horizontal_edge = false;
@@ -521,7 +524,7 @@ class _area_comp {
 };
 
 void
-TriangleMesh::slice(const std::vector<double> &z, std::vector<ExPolygons>* layers)
+TriangleMesh::slice(const std::vector<float> &z, std::vector<ExPolygons>* layers)
 {
     std::vector<Polygons> layers_p;
     this->slice(z, &layers_p);
diff --git a/xs/src/TriangleMesh.hpp b/xs/src/TriangleMesh.hpp
index 055817739..f20340b42 100644
--- a/xs/src/TriangleMesh.hpp
+++ b/xs/src/TriangleMesh.hpp
@@ -30,8 +30,8 @@ class TriangleMesh
     void translate(float x, float y, float z);
     void align_to_origin();
     void rotate(double angle, Point* center);
-    void slice(const std::vector<double> &z, std::vector<Polygons>* layers);
-    void slice(const std::vector<double> &z, std::vector<ExPolygons>* layers);
+    void slice(const std::vector<float> &z, std::vector<Polygons>* layers);
+    void slice(const std::vector<float> &z, std::vector<ExPolygons>* layers);
     TriangleMeshPtrs split() const;
     void merge(const TriangleMesh* mesh);
     void horizontal_projection(ExPolygons &retval) const;
diff --git a/xs/src/myinit.h b/xs/src/myinit.h
index 0156f64dc..14e25fd43 100644
--- a/xs/src/myinit.h
+++ b/xs/src/myinit.h
@@ -23,6 +23,7 @@ extern "C" {
 #define PI 3.141592653589793238
 #define scale_(val) (val / SCALING_FACTOR)
 #define unscale(val) (val * SCALING_FACTOR)
+#define SCALED_EPSILON scale_(EPSILON)
 typedef long coord_t;
 typedef double coordf_t;
 
diff --git a/xs/xsp/TriangleMesh.xsp b/xs/xsp/TriangleMesh.xsp
index f026390c4..26670a1db 100644
--- a/xs/xsp/TriangleMesh.xsp
+++ b/xs/xsp/TriangleMesh.xsp
@@ -137,8 +137,12 @@ SV*
 TriangleMesh::slice(z)
     std::vector<double>* z
     CODE:
+        // convert doubles to floats
+        std::vector<float> z_f(z->begin(), z->end());
+        delete z;
+        
         std::vector<ExPolygons> layers;
-        THIS->slice(*z, &layers);
+        THIS->slice(z_f, &layers);
         
         AV* layers_av = newAV();
         av_extend(layers_av, layers.size()-1);