diff a/dos2unix.c b/dos2unix.c
--- a/dos2unix.c
+++ b/dos2unix.c
@@ -213,13 +213,15 @@ int convert(char *fn, int convType) {
 
     /* if we're not working with stdin, close source (in) */
     if (fn != NULL) {
-        if (fclose(in) != 0, in = NULL)
+        if (fclose(in) != 0)
             BAIL (-2, argv0);
+        in = NULL;
     }
 
     /* close temp file (out) */
-    if (fclose(out) != 0, out = NULL)
+    if (fclose(out) != 0)
         BAIL (-2, argv0);
+    out = NULL;
 
 
     /* figure out conversion type */