diff --git a/src/file.cpp b/src/file.cpp
index 89ec83a1..6d94ee51 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -181,7 +181,7 @@ void FileBase::seek(off_t off, int whence)
 }
 
 
-off_t FileBase::tell()
+off_t FileBase::tell() const
 {
     if (!isOpen())
         throwIOException("bad tell");
@@ -253,7 +253,7 @@ void InputFile::seek(off_t off, int whence)
 }
 
 
-off_t InputFile::tell()
+off_t InputFile::tell() const
 {
     return super::tell();
 }
diff --git a/src/file.h b/src/file.h
index cc609070..dc49fe1e 100644
--- a/src/file.h
+++ b/src/file.h
@@ -60,7 +60,7 @@ protected:
     virtual int readx(void *buf, int len);
     virtual void write(const void *buf, int len);
     virtual void seek(off_t off, int whence);
-    virtual off_t tell();
+    virtual off_t tell() const;
 
     int _fd;
     int _flags;
@@ -93,7 +93,7 @@ public:
     virtual int readx(void * buf, int len);
 
     virtual void seek(off_t off, int whence);
-    virtual off_t tell();
+    virtual off_t tell() const;
 };