diff --git a/src/common/mm_write_cache_io.cpp b/src/common/mm_write_cache_io.cpp
index c68ccb524..cb043a595 100644
--- a/src/common/mm_write_cache_io.cpp
+++ b/src/common/mm_write_cache_io.cpp
@@ -37,7 +37,7 @@ mm_write_cache_io_c::setFilePointer(int64 offset,
     : seek_end       == mode ? get_size()       - offset
     :                          getFilePointer() + offset;
 
-  if (new_pos == getFilePointer())
+  if (new_pos == static_cast<int64_t>(getFilePointer()))
     return;
 
   flush_cache();
diff --git a/src/common/mm_write_cache_io.h b/src/common/mm_write_cache_io.h
index af51e4414..f2a43e160 100644
--- a/src/common/mm_write_cache_io.h
+++ b/src/common/mm_write_cache_io.h
@@ -21,7 +21,7 @@
 class MTX_DLL_API mm_write_cache_io_c: public mm_proxy_io_c {
 protected:
   memory_cptr m_cache;
-  int m_cache_pos;
+  size_t m_cache_pos;
 
 public:
   mm_write_cache_io_c(mm_io_c *p_out, int cache_size, bool p_delete_out = true);