diff --git a/src/OpenMesh/Core/IO/reader/OFFReader.cc b/src/OpenMesh/Core/IO/reader/OFFReader.cc
index b918d9f9..415eba01 100644
--- a/src/OpenMesh/Core/IO/reader/OFFReader.cc
+++ b/src/OpenMesh/Core/IO/reader/OFFReader.cc
@@ -589,7 +589,7 @@ bool _OFFReader_::can_u_read(std::istream& _is) const
   _is.getline(line, LINE_LEN);
   p = line;
 
-  int remainingChars = _is.gcount();
+  size_t remainingChars = _is.gcount();
 
   bool vertexDimensionTooHigh = false;
 
@@ -615,7 +615,12 @@ bool _OFFReader_::can_u_read(std::istream& _is) const
     return false;
 
   p += 4;
-  remainingChars -= 4;
+
+  // Detect possible garbage and make sure, we don't have an underflow
+  if ( remainingChars >= 4 )
+    remainingChars -= 4;
+  else 
+    remainingChars = 0;
 
   if ( ( remainingChars >= 6 ) && ( strncmp(p, "BINARY", 6) == 0 ) )
     options_+= Options::Binary;
diff --git a/src/OpenMesh/Core/IO/reader/PLYReader.cc b/src/OpenMesh/Core/IO/reader/PLYReader.cc
index e456d24c..af7af19b 100644
--- a/src/OpenMesh/Core/IO/reader/PLYReader.cc
+++ b/src/OpenMesh/Core/IO/reader/PLYReader.cc
@@ -892,7 +892,7 @@ bool _PLYReader_::can_u_read(std::istream& _is) const {
         return false;
     }
 
-    unsigned int streamPos = _is.tellg();
+    size_t streamPos = _is.tellg();
     _is >> keyword;
     while (keyword != "end_header") {
 
diff --git a/src/OpenMesh/Core/IO/reader/STLReader.cc b/src/OpenMesh/Core/IO/reader/STLReader.cc
index 3cf7b8a4..96d92672 100644
--- a/src/OpenMesh/Core/IO/reader/STLReader.cc
+++ b/src/OpenMesh/Core/IO/reader/STLReader.cc
@@ -365,15 +365,15 @@ check_stl_type(const std::string& _filename) const
   // read number of triangles
   char dummy[100];
   fread(dummy, 1, 80, in);
-  unsigned int nT = read_int(in, swapFlag);
+  size_t nT = read_int(in, swapFlag);
 
 
   // compute file size from nT
-  unsigned int binary_size = 84 + nT*50;
+  size_t binary_size = 84 + nT*50;
 
 
   // get actual file size
-  unsigned int file_size(0);
+  size_t file_size(0);
   rewind(in);
   while (!feof(in))
     file_size += fread(dummy, 1, 100, in);