diff --git a/BGL/include/CGAL/boost/graph/IO/polygon_mesh_io.h b/BGL/include/CGAL/boost/graph/IO/polygon_mesh_io.h
index fd4f46893e2..3a89700f6a7 100644
--- a/BGL/include/CGAL/boost/graph/IO/polygon_mesh_io.h
+++ b/BGL/include/CGAL/boost/graph/IO/polygon_mesh_io.h
@@ -11,6 +11,7 @@
 #define CGAL_BOOST_GRAPH_POLYGON_MESH_IO_H
 
 #include <CGAL/boost/graph/io.h>
+#include <CGAL/IO/polygon_soup_io.h>
 
 namespace CGAL {
 
diff --git a/BGL/include/CGAL/boost/graph/io.h b/BGL/include/CGAL/boost/graph/io.h
index 2deabecc2e6..04d4733d56f 100644
--- a/BGL/include/CGAL/boost/graph/io.h
+++ b/BGL/include/CGAL/boost/graph/io.h
@@ -21,4 +21,6 @@
 #include <CGAL/boost/graph/IO/VTK.h>
 #include <CGAL/boost/graph/IO/WRL.h>
 
+#include <CGAL/boost/graph/IO/polygon_mesh_io.h>
+
 #endif // CGAL_BOOST_GRAPH_IO_H
diff --git a/Stream_support/include/CGAL/IO/GOCAD.h b/Stream_support/include/CGAL/IO/GOCAD.h
index e7609d30d32..398a99e8d52 100644
--- a/Stream_support/include/CGAL/IO/GOCAD.h
+++ b/Stream_support/include/CGAL/IO/GOCAD.h
@@ -284,7 +284,6 @@ bool write_GOCAD(const char* fname,
   return IO::internal::write_GOCAD(os, fname, points, polygons, np);
 }
 
-
 /*!
   \ingroup GocadIoFuncs
 
diff --git a/Stream_support/include/CGAL/IO/OBJ.h b/Stream_support/include/CGAL/IO/OBJ.h
index 0427f71a151..980a0aa07ab 100644
--- a/Stream_support/include/CGAL/IO/OBJ.h
+++ b/Stream_support/include/CGAL/IO/OBJ.h
@@ -19,6 +19,7 @@
 
 #include <boost/range/value_type.hpp>
 
+#include <fstream>
 #include <iostream>
 #include <sstream>
 #include <string>
@@ -209,7 +210,7 @@ template <typename PointRange,
 bool write_OBJ(std::ostream& os,
                const PointRange& points,
                const PolygonRange& polygons,
-               const CGAL_BGL_NP_CLASS& )
+               const CGAL_BGL_NP_CLASS&)
 {
   Generic_writer<std::ostream, File_writer_wavefront> writer(os);
   return writer(points, polygons);
diff --git a/Stream_support/include/CGAL/IO/OFF/File_scanner_OFF.h b/Stream_support/include/CGAL/IO/OFF/File_scanner_OFF.h
index ba839c7e86e..9ea5a15b0c3 100644
--- a/Stream_support/include/CGAL/IO/OFF/File_scanner_OFF.h
+++ b/Stream_support/include/CGAL/IO/OFF/File_scanner_OFF.h
@@ -18,8 +18,10 @@
 #define CGAL_IO_OFF_FILE_SCANNER_OFF_H
 
 #include <CGAL/config.h>
+
 #include <CGAL/IO/binary_file_io.h>
 #include <CGAL/IO/OFF/File_header_OFF.h>
+#include <CGAL/IO/io.h>
 
 #include <boost/cstdint.hpp>
 
diff --git a/Stream_support/include/CGAL/IO/PLY.h b/Stream_support/include/CGAL/IO/PLY.h
index 63e9d4f4a9e..39b23332dd8 100644
--- a/Stream_support/include/CGAL/IO/PLY.h
+++ b/Stream_support/include/CGAL/IO/PLY.h
@@ -21,6 +21,14 @@
 
 #include <boost/utility/enable_if.hpp>
 
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
 namespace CGAL {
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/Stream_support/include/CGAL/IO/STL.h b/Stream_support/include/CGAL/IO/STL.h
index 2111e62b1bb..5af423a21b5 100644
--- a/Stream_support/include/CGAL/IO/STL.h
+++ b/Stream_support/include/CGAL/IO/STL.h
@@ -23,6 +23,8 @@
 #include <boost/range/value_type.hpp>
 
 #include <iostream>
+#include <fstream>
+#include <string>
 
 namespace CGAL {
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -173,8 +175,8 @@ bool read_STL(const std::string& fname, PointRange& points, TriangleRange& facet
  */
 template <class PointRange, class TriangleRange>
 bool write_STL(std::ostream& out,
-                        const PointRange& points,
-                        const TriangleRange& facets)
+               const PointRange& points,
+               const TriangleRange& facets)
 {
   typedef typename boost::range_value<TriangleRange>::type            Triangle;
   typedef typename boost::range_value<PointRange>::type               Point;
diff --git a/Stream_support/include/CGAL/IO/VTK.h b/Stream_support/include/CGAL/IO/VTK.h
index ff2ca668cee..4368c837786 100644
--- a/Stream_support/include/CGAL/IO/VTK.h
+++ b/Stream_support/include/CGAL/IO/VTK.h
@@ -17,7 +17,9 @@
 
 #include <CGAL/IO/VTK/VTK_reader.h>
 #include <CGAL/IO/VTK/VTK_writer.h>
+
 #include <CGAL/boost/graph/Named_function_parameters.h>
+
 #ifdef CGAL_USE_VTK
 #include <vtkSmartPointer.h>
 #include <vtkCommand.h>
@@ -25,9 +27,11 @@
 #include <vtkXMLPolyDataReader.h>
 #include <vtkPointSet.h>
 #include <vtkPolyData.h>
+
 namespace CGAL {
 namespace IO {
 namespace internal {
+
 //append the content of poly_data to a soup.
 template <typename PointRange, typename PolygonRange, typename NamedParameters>
 bool vtkPointSet_to_polygon_soup(vtkPointSet* poly_data,
@@ -103,7 +107,7 @@ bool read_VTP(const char* fname,
 }
 
 template <typename PointRange, typename PolygonRange, typename NamedParameters>
-bool read_VTP(const std::string&  fname,
+bool read_VTP(const std::string& fname,
               PointRange& points,
               PolygonRange& polygons,
               const NamedParameters& np)
diff --git a/Stream_support/include/CGAL/IO/WKT.h b/Stream_support/include/CGAL/IO/WKT.h
index 216f0bd1bff..c59e532f999 100644
--- a/Stream_support/include/CGAL/IO/WKT.h
+++ b/Stream_support/include/CGAL/IO/WKT.h
@@ -34,6 +34,7 @@
 #include <boost/geometry/io/wkt/write.hpp>
 
 #include <iostream>
+#include <fstream>
 #include <sstream>
 #include <string>
 
diff --git a/Stream_support/include/CGAL/IO/io.h b/Stream_support/include/CGAL/IO/io.h
index 5baabd975ba..f074cdef86e 100644
--- a/Stream_support/include/CGAL/IO/io.h
+++ b/Stream_support/include/CGAL/IO/io.h
@@ -14,17 +14,17 @@
 //
 // Author(s)     : Andreas Fabri
 
-
 #ifndef CGAL_IO_H
 #define CGAL_IO_H
 
 #include <CGAL/disable_warnings.h>
 
-#include <CGAL/assertions.h>
-#include <CGAL/tags.h>
 #include <CGAL/IO/io_tags.h>
 #include <CGAL/IO/Color.h>
+
+#include <CGAL/assertions.h>
 #include <CGAL/Fraction_traits.h>
+#include <CGAL/tags.h>
 
 #include <cstdio>
 #include <cctype>