diff --git a/Envelope_3/include/CGAL/Envelope_3/Envelope_divide_and_conquer_3.h b/Envelope_3/include/CGAL/Envelope_3/Envelope_divide_and_conquer_3.h
index ad237a7e99f..42aa64669a1 100644
--- a/Envelope_3/include/CGAL/Envelope_3/Envelope_divide_and_conquer_3.h
+++ b/Envelope_3/include/CGAL/Envelope_3/Envelope_divide_and_conquer_3.h
@@ -1341,7 +1341,7 @@ protected:
     for (auto vi = result.vertices_begin(); vi != result.vertices_end(); ++vi) {
       Vertex_handle vh = vi;
 
-      all_ok &= (vh->env_is_set());
+      all_ok &= (vh->is_env_set());
       CGAL_assertion_msg(all_ok, "data not set over vertex");
       all_ok &= (!vh->has_no_env_data());
 
@@ -1354,7 +1354,7 @@ protected:
     {
       Halfedge_handle hh = hi;
 
-      all_ok &= (hh->env_is_set());
+      all_ok &= (hh->is_env_set());
       if (!all_ok) std::cerr << "edge: " << hh->curve() << std::endl;
       CGAL_assertion_msg(all_ok, "data not set over edge");
       all_ok &= (!hh->has_no_env_data());
@@ -1367,7 +1367,7 @@ protected:
 
     for (auto fi = result.faces_begin(); fi != result.faces_end(); ++fi) {
       Face_handle fh = fi;
-      all_ok &= (fh->env_is_set());
+      all_ok &= (fh->is_env_set());
       CGAL_assertion_msg(all_ok, "data not set over face");
     }
     return all_ok;
diff --git a/Envelope_3/include/CGAL/Envelope_3/Envelope_overlay_2.h b/Envelope_3/include/CGAL/Envelope_3/Envelope_overlay_2.h
index 78dc81612ea..a7d5773ce34 100644
--- a/Envelope_3/include/CGAL/Envelope_3/Envelope_overlay_2.h
+++ b/Envelope_3/include/CGAL/Envelope_3/Envelope_overlay_2.h
@@ -63,7 +63,7 @@ public:
   /* void print_face(Face_handle fh) {
    *   std::cout << (fh->is_unbounded() ? "unbounded" : "bounded");
    *
-   *   if (fh->env_is_set()) {
+   *   if (fh->is_env_set()) {
    *     std::cout << " #data= " << fh->env_data_size();
    *     if (fh->env_data_size() > 0)
    *       std::cout << " data= " << fh->env_data_front();
@@ -98,7 +98,7 @@ public:
    *     Vertex_handle vh = vit;
    *     std::cout << vh->point();
    *
-   *      if (vh->env_is_set()) {
+   *      if (vh->is_env_set()) {
    *       std::cout << " #data= " << vh->env_data_size();
    *       if (vh->env_data_size() > 0)
    *         std::cout << " data= " << vh->env_data_front();
@@ -125,7 +125,7 @@ public:
    *     Halfedge_handle hh = hit;
    *     std::cout << hh->curve();
    *
-   *     if (hh->env_is_set()) {
+   *     if (hh->is_env_set()) {
    *       std::cout << " #data= " << hh->env_data_size();
    *       if (hh->env_data_size() > 0)
    *         std::cout << " data= " << hh->env_data_front();
diff --git a/Envelope_3/include/CGAL/Envelope_3/Envelope_pm_dcel.h b/Envelope_3/include/CGAL/Envelope_3/Envelope_pm_dcel.h
index a7ecfc45f46..31e114b2f48 100644
--- a/Envelope_3/include/CGAL/Envelope_3/Envelope_pm_dcel.h
+++ b/Envelope_3/include/CGAL/Envelope_3/Envelope_pm_dcel.h
@@ -39,19 +39,19 @@ protected:
   Data_container m_env_data;
 
   /*! Indicates that the data (surfaces) have been set already */
-  bool m_is_set;
+  bool m_is_env_set;
 
   // the decision that was made
   Dac_decision m_decision;
 public:
   /*! Constructor */
-  Dcel_info() : m_is_set(false), m_decision(DAC_DECISION_NOT_SET) {}
+  Dcel_info() : m_is_env_set(false), m_decision(DAC_DECISION_NOT_SET) {}
 
   /*! \brief returns true iff data has been set already */
-  bool env_is_set() const { return m_is_set; }
+  bool is_env_set() const { return m_is_env_set; }
 
   /*! \brief resets the flag  */
-  void set_is_set(bool flag) { m_is_set = flag; }
+  void set_is_env_set(bool flag) { m_is_env_set = flag; }
 
   bool is_decision_set() { return (m_decision != DAC_DECISION_NOT_SET); }
 
@@ -85,7 +85,7 @@ public:
   /*! Check whether the data is set to be empty
    */
   bool has_no_env_data() const
-  { return (m_is_set && (env_data_size() == 0)); }
+  { return (m_is_env_set && (env_data_size() == 0)); }
 
   /*! Obtain the first data object associated with the cell.
    * \pre m_env_data.size() is not 0.
@@ -129,7 +129,7 @@ public:
    */
   void set_no_env_data() {
     clear_env_data();
-    m_is_set = true;
+    m_is_env_set = true;
   }
 
    /*! Add a data object to the face.
@@ -137,7 +137,7 @@ public:
    */
   void add_env_data(const Data& data) {
     m_env_data.push_back(data);
-    m_is_set = true;
+    m_is_env_set = true;
   }
 
   /*! Add a range of data objects to the face.
@@ -147,14 +147,14 @@ public:
   template <typename InputIterator>
   void add_env_data(InputIterator begin, InputIterator end) {
     for (auto it = begin; it != end; ++it) m_env_data.push_back(*it);
-    m_is_set = true;
+    m_is_env_set = true;
   }
 
   /*! Clear the data objects.
    */
   void clear_env_data() {
     m_env_data.clear();
-    m_is_set = false;
+    m_is_env_set = false;
   }
 
   /*! Check whether the set of data objects in the input range is equal to our
@@ -162,7 +162,7 @@ public:
    */
   template <typename InputIterator>
   bool is_equal_env_data(InputIterator begin, InputIterator end) const {
-    if (! env_is_set()) return false;
+    if (! is_env_set()) return false;
 
     // insert the input data objects into a set
     std::set<Data> input_data(begin, end);
@@ -173,7 +173,7 @@ public:
 
   template <typename InputIterator>
   bool has_equal_env_data(InputIterator begin, InputIterator end) const {
-    if (! env_is_set()) return false;
+    if (! is_env_set()) return false;
 
     // insert the input data objects into a set
     std::set<Data> input_data(begin, end);