diff --git a/src/osgPlugins/stl/ReaderWriterSTL.cpp b/src/osgPlugins/stl/ReaderWriterSTL.cpp
index 1a1eb0352..2bc72a837 100644
--- a/src/osgPlugins/stl/ReaderWriterSTL.cpp
+++ b/src/osgPlugins/stl/ReaderWriterSTL.cpp
@@ -405,8 +405,8 @@ bool fileComesFromMagics(FILE *fp, osg::Vec4& magicsColor)
 
     ::rewind(fp);
 
-    size_t bytes_read = fread((void*) &header, sizeof(header), 1, fp);
-    if (bytes_read!=sizeof(header)) return false;
+    if (fread((void*) &header, sizeof(header), 1, fp) != 1)
+        return false;
 
     if (::fseek(fp, sizeof_StlHeader, SEEK_SET)!=0)
     {