diff --git a/src/OpenMesh/Core/IO/reader/OFFReader.cc b/src/OpenMesh/Core/IO/reader/OFFReader.cc
index 9f9494fc..808a5b3d 100644
--- a/src/OpenMesh/Core/IO/reader/OFFReader.cc
+++ b/src/OpenMesh/Core/IO/reader/OFFReader.cc
@@ -641,7 +641,7 @@ bool _OFFReader_::can_u_read(std::istream& _is) const
   _is.getline(line, LINE_LEN);
   p = line;
 
-  size_t remainingChars = _is.gcount();
+  std::streamsize remainingChars = _is.gcount();
 
   bool vertexDimensionTooHigh = false;
 
diff --git a/src/OpenMesh/Core/IO/reader/PLYReader.cc b/src/OpenMesh/Core/IO/reader/PLYReader.cc
index bde7ef00..2084308b 100644
--- a/src/OpenMesh/Core/IO/reader/PLYReader.cc
+++ b/src/OpenMesh/Core/IO/reader/PLYReader.cc
@@ -901,7 +901,7 @@ bool _PLYReader_::can_u_read(std::istream& _is) const {
         return false;
     }
 
-    size_t streamPos = _is.tellg();
+    std::streamoff streamPos = _is.tellg();
     _is >> keyword;
     while (keyword != "end_header") {