diff --git a/include/QF/progs.h b/include/QF/progs.h
index 769fdb533..5a00afd46 100644
--- a/include/QF/progs.h
+++ b/include/QF/progs.h
@@ -1942,7 +1942,8 @@ struct progs_s {
 	pr_def_t   *pr_fielddefs;
 	dstatement_t *pr_statements;
 	pr_type_t  *pr_globals;
-	unsigned    globals_size;
+	pr_uint_t   globals_size;
+	pr_uint_t   null_size;		///< size of block considered null page
 	pr_uivec4_t pr_bases;		///< base registers (index in opcode)
 	///@}
 
diff --git a/libs/gamecode/pr_exec.c b/libs/gamecode/pr_exec.c
index 200e0c0d8..89890908f 100644
--- a/libs/gamecode/pr_exec.c
+++ b/libs/gamecode/pr_exec.c
@@ -351,7 +351,7 @@ PR_LeaveFunction (progs_t *pr, int to_engine)
 VISIBLE void
 PR_BoundsCheckSize (progs_t *pr, pr_ptr_t addr, unsigned size)
 {
-	if (addr < (pr_ptr_t) (pr->pr_return - pr->pr_globals))
+	if (addr < pr->null_size)
 		PR_RunError (pr, "null pointer access");
 	if (addr >= pr->globals_size
 		|| size > (unsigned) (pr->globals_size - addr))
diff --git a/libs/gamecode/pr_resolve.c b/libs/gamecode/pr_resolve.c
index 864baa443..008c1abed 100644
--- a/libs/gamecode/pr_resolve.c
+++ b/libs/gamecode/pr_resolve.c
@@ -142,6 +142,7 @@ PR_ResolveGlobals (progs_t *pr)
 			goto error;
 		pr->pr_param_alignment = G_INT (pr, def->ofs);
 	}
+	pr->null_size = pr->pr_return - pr->pr_globals;
 	memcpy (pr->pr_real_params, pr->pr_params, sizeof (pr->pr_params));
 	if (!pr->globals.ftime) {//FIXME double time
 		if ((def = PR_FindGlobal (pr, "time")))