--- ghostscript-9.21/psi/zmisc3.c.orig	2017-03-16 11:12:02.000000000 +0100
+++ ghostscript-9.21/psi/zmisc3.c	2017-05-02 14:43:41.000000000 +0200
@@ -56,6 +56,12 @@ zeqproc(i_ctx_t *i_ctx_p)
     ref2_t stack[MAX_DEPTH + 1];
     ref2_t *top = stack;
 
+    if (ref_stack_count(&o_stack) < 2)
+        return_error(gs_error_stackunderflow);
+    if (!r_is_array(op - 1) || !r_is_array(op)) {
+        return_error(gs_error_typecheck);
+    }
+
     make_array(&stack[0].proc1, 0, 1, op - 1);
     make_array(&stack[0].proc2, 0, 1, op);
     for (;;) {
--- ghostscript-9.21/psi/zfrsd.c.orig	2017-03-16 11:12:02.000000000 +0100
+++ ghostscript-9.21/psi/zfrsd.c	2017-05-02 14:45:35.000000000 +0200
@@ -49,13 +49,20 @@ zrsdparams(i_ctx_t *i_ctx_p)
     ref *pFilter;
     ref *pDecodeParms;
     int Intent = 0;
-    bool AsyncRead;
+    bool AsyncRead = false;
     ref empty_array, filter1_array, parms1_array;
     uint i;
-    int code;
+    int code = 0;
+
+    if (ref_stack_count(&o_stack) < 1)
+        return_error(gs_error_stackunderflow);
+    if (!r_has_type(op, t_dictionary) && !r_has_type(op, t_null)) {
+        return_error(gs_error_typecheck);
+    }
 
     make_empty_array(&empty_array, a_readonly);
-    if (dict_find_string(op, "Filter", &pFilter) > 0) {
+    if (r_has_type(op, t_dictionary)
+        && dict_find_string(op, "Filter", &pFilter) > 0) {
         if (!r_is_array(pFilter)) {
             if (!r_has_type(pFilter, t_name))
                 return_error(gs_error_typecheck);
@@ -94,12 +101,13 @@ zrsdparams(i_ctx_t *i_ctx_p)
                 return_error(gs_error_typecheck);
         }
     }
-    code = dict_int_param(op, "Intent", 0, 3, 0, &Intent);
+    if (r_has_type(op, t_dictionary))
+        code = dict_int_param(op, "Intent", 0, 3, 0, &Intent);
     if (code < 0 && code != gs_error_rangecheck) /* out-of-range int is ok, use 0 */
         return code;
-    if ((code = dict_bool_param(op, "AsyncRead", false, &AsyncRead)) < 0
-        )
-        return code;
+    if (r_has_type(op, t_dictionary))
+        if ((code = dict_bool_param(op, "AsyncRead", false, &AsyncRead)) < 0)
+            return code;
     push(1);
     op[-1] = *pFilter;
     if (pDecodeParms)