--- a/ExternalStream.st	Fri Apr 07 14:33:23 2017 +0200
+++ b/ExternalStream.st	Fri Apr 07 16:42:20 2017 +0200
@@ -2211,12 +2211,20 @@
 #ifdef __win32__
             RETURN(__MKEXTERNALADDRESS(_get_osfhandle(fileno(__FILEVal(_handle)))));
 #else
-            RETURN (__MKINT(fileno(__FILEVal(_handle))));
+            FILE *file = __FILEVal(_handle);
+            if (file != NULL) {
+                int fileNo = fileno(file);
+                if (fileNo >= 0) {
+                    RETURN (__MKINT(fileNo));
+                }
+            }    
 #endif
         }
     }
 %}.
     ^ handle
+
+    "Modified: / 07-04-2017 / 16:34:40 / cg"
 !
 
 filePointer