diff --git a/PlugIns/EXRCodec/src/O_IStream.cpp b/PlugIns/EXRCodec/src/O_IStream.cpp
index 6f668d5..eba9ac7 100644
--- a/PlugIns/EXRCodec/src/O_IStream.cpp
+++ b/PlugIns/EXRCodec/src/O_IStream.cpp
@@ -39,11 +39,11 @@ bool O_IStream::read(char c[], int n) {
     return _stream.eof();
 }
 
-Int64 O_IStream::tellg() {
+uint64_t O_IStream::tellg() {
     return _stream.getCurrentPtr() - _stream.getPtr();
 }
 
-void O_IStream::seekg(Int64 pos) {
+void O_IStream::seekg(uint64_t pos) {
     _stream.seek(pos);
 }
 
diff --git a/PlugIns/EXRCodec/src/O_IStream.h b/PlugIns/EXRCodec/src/O_IStream.h
index 8eb09d8..dc301ae 100644
--- a/PlugIns/EXRCodec/src/O_IStream.h
+++ b/PlugIns/EXRCodec/src/O_IStream.h
@@ -46,8 +46,8 @@ public:
         IStream (file_name), _stream(stream) {}
 
     bool    read (char c[], int n) override;
-    Imf::Int64   tellg () override;
-    void    seekg (Imf::Int64 pos) override;
+    virtual uint64_t   tellg () override;
+    virtual void    seekg (uint64_t pos) override;
     void    clear () override;
 
 private: