diff --git a/src/reader.cpp b/src/reader.cpp
index fd5c1bc348..f2652d868d 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -16,8 +16,6 @@
 
 #include "error.h"
 
-#include <cstring>
-
 using namespace LAMMPS_NS;
 
 // only proc 0 calls methods of this class, except for constructor/destructor
@@ -44,18 +42,7 @@ void Reader::open_file(const std::string &file)
     if (!fp) error->one(FLERR,"Cannot open compressed file for reading");
   } else {
     compressed = 0;
-
-    // leleslx: if there is .bin ending
-    std::size_t dot = file.find_last_of('.');
-    char reading_mode[3] = "r"; 
-    if (dot != std::string::npos) {
-      const std::string ext = file.substr(dot + 1);
-      if ("bin" == ext){
-        sprintf(reading_mode, "rb");
-      }
-    }
-
-    fp = fopen(file.c_str(), reading_mode);
+    fp = fopen(file.c_str(),"r");
   }
 
   if (!fp) error->one(FLERR,"Cannot open file {}: {}", file, utils::getsyserror());
diff --git a/src/reader_native_bin.cpp b/src/reader_native_bin.cpp
index 11bbbd3150..4acaf1946d 100644
--- a/src/reader_native_bin.cpp
+++ b/src/reader_native_bin.cpp
@@ -43,6 +43,23 @@ ReaderNativeBin::~ReaderNativeBin()
   memory->destroy(fieldindex);
 }
 
+/* ----------------------------------------------------------------------
+   overload the open_file function to open the binary file
+------------------------------------------------------------------------- */
+void ReaderNativeBin::open_file(const std::string &file)
+{
+  if (fp != nullptr) close_file();
+
+  if (platform::has_compress_extension(file)) {
+    error->one(FLERR,"Compressed binary files are not supported");
+  } else {
+    compressed = 0;
+    fp = fopen(file.c_str(), "rb");
+  }
+
+  if (!fp) error->one(FLERR,"Cannot open file {}: {}", file, utils::getsyserror());
+}
+
 /* ----------------------------------------------------------------------
    read and return time stamp from dump file
    if first read reaches end-of-file, return 1 so caller can open next file
diff --git a/src/reader_native_bin.h b/src/reader_native_bin.h
index b0149fc9bd..6e2c71da61 100644
--- a/src/reader_native_bin.h
+++ b/src/reader_native_bin.h
@@ -38,14 +38,16 @@ class ReaderNativeBin : public ReaderNative {
   bigint read_header(double[3][3], int &, int &, int, int, int *, char **, int, int, int &, int &,
                      int &, int &);
   void read_atoms(int, int, double **);
+  void open_file(const std::string &);
 
  private:
   int revision;
   char *magic_string;
   char *unit_style;
-  int size_one;
-  int maxbuf = 1;
+
+  int size_one;    // number of double for one atom
   double *buf;
+  int maxbuf = 1;    // maximum buffer size
 
   void read_buf(void *, size_t, size_t);
   void read_double_chunk(size_t);