diff --git a/xs/src/admesh/stl.h b/xs/src/admesh/stl.h
index b2be5830e4..449e2b5aa6 100644
--- a/xs/src/admesh/stl.h
+++ b/xs/src/admesh/stl.h
@@ -24,6 +24,7 @@
 #define __admesh_stl__
 
 #include <stdio.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -33,11 +34,15 @@ extern "C" {
 #define STL_MIN(A,B) ((A)<(B)? (A):(B))
 #define ABS(X)  ((X) < 0 ? -(X) : (X))
 
+// Size of the binary STL header, free form.
 #define LABEL_SIZE             80
+// Binary STL, length of the "number of faces" counter.
 #define NUM_FACET_SIZE         4
+// Binary STL, sizeof header + number of faces.
 #define HEADER_SIZE            84
 #define STL_MIN_FILE_SIZE      284
 #define ASCII_LINES_PER_FACET  7
+// Comparing an edge by memcmp, 2x3x4 bytes = 24
 #define SIZEOF_EDGE_SORT       24
 
 typedef struct {
@@ -70,14 +75,17 @@ typedef struct {
 } stl_edge;
 
 typedef struct stl_hash_edge {
-  unsigned       key[6];
+  // Key of a hash edge: 2x binary copy of a floating point vertex.
+  uint32_t       key[6];
   int            facet_number;
   int            which_edge;
   struct stl_hash_edge  *next;
 } stl_hash_edge;
 
 typedef struct {
+  // Index of a neighbor facet.
   int   neighbor[3];
+  // Index of an opposite vertex at the neighbor face.
   char  which_vertex_not[3];
 } stl_neighbors;
 
diff --git a/xs/src/libslic3r/TriangleMesh.cpp b/xs/src/libslic3r/TriangleMesh.cpp
index 437bea44c7..4a569ed406 100644
--- a/xs/src/libslic3r/TriangleMesh.cpp
+++ b/xs/src/libslic3r/TriangleMesh.cpp
@@ -55,10 +55,10 @@ TriangleMesh& TriangleMesh::operator= (TriangleMesh other)
 }
 
 void
-TriangleMesh::swap(TriangleMesh &first, TriangleMesh &second)
+TriangleMesh::swap(TriangleMesh &other)
 {
-    std::swap(first.repaired,            second.repaired);
-    std::swap(first.stl,                 second.stl);
+    std::swap(this->stl,      other.stl);
+    std::swap(this->repaired, other.repaired);
 }
 
 TriangleMesh::~TriangleMesh() {
diff --git a/xs/src/libslic3r/TriangleMesh.hpp b/xs/src/libslic3r/TriangleMesh.hpp
index 196ef17c01..b10e3fae69 100644
--- a/xs/src/libslic3r/TriangleMesh.hpp
+++ b/xs/src/libslic3r/TriangleMesh.hpp
@@ -22,7 +22,7 @@ class TriangleMesh
     TriangleMesh();
     TriangleMesh(const TriangleMesh &other);
     TriangleMesh& operator= (TriangleMesh other);
-    void swap(TriangleMesh &first, TriangleMesh &second);
+    void swap(TriangleMesh &other);
     ~TriangleMesh();
     void ReadSTLFile(const std::string &input_file);
     void write_ascii(const std::string &output_file);