Index: bindings/tcl/tclrrd.c
===================================================================
--- bindings/tcl/tclrrd.c.orig
+++ bindings/tcl/tclrrd.c
@@ -472,6 +472,12 @@ static int Rrd_Graph(
     char    **argv2;
     CONST84 char *save;
 
+    if (argc < 2) {
+        Tcl_AppendResult(interp, "RRD Error: needs image filename",
+                         (char *) NULL);
+        return TCL_ERROR;
+    }
+
     /*
      * If the "filename" is a Tcl fileID, then arrange for rrd_graph() to write to
      * that file descriptor.  Will this work with windoze?  I have no idea.
@@ -597,6 +603,12 @@ static int Rrd_Resize(
 {
     char    **argv2;
 
+    if (argc < 2) {
+        Tcl_AppendResult(interp, "RRD Error: needs rrd filename",
+                         (char *) NULL);
+        return TCL_ERROR;
+    }
+
     argv2 = getopt_init(argc, argv);
     rrd_resize(argc, argv2);
     getopt_cleanup(argc, argv2);