diff --git a/tools/qfprogs/source/modules.c b/tools/qfprogs/source/modules.c
index da6c84efb..8faa24956 100644
--- a/tools/qfprogs/source/modules.c
+++ b/tools/qfprogs/source/modules.c
@@ -55,13 +55,17 @@ dump_methods (progs_t *pr, pr_method_list_t *methods, int class)
 {
 	int         i;
 	char        mark = class ? '+' : '-';
+	const char *sel_id;
 
 	while (methods) {
 		pr_method_t *method = methods->method_list;
 		for (i = 0; i < methods->method_count; i++) {
-			printf ("        %c%s %d @ %d\n", mark,
-					PR_GetString (pr, method->method_name.sel_id),
-					method->method_imp, POINTER_TO_PROG (pr, method));
+			if (PR_StringValid (pr, method->method_name.sel_id))
+				sel_id = PR_GetString (pr, method->method_name.sel_id);
+			else
+				sel_id = "<invalid string>";
+			printf ("        %c%s %d @ %d\n", mark, sel_id, method->method_imp,
+					POINTER_TO_PROG (pr, method));
 			method++;
 		}
 		methods = &G_STRUCT (pr, pr_method_list_t, methods->method_next);
@@ -72,14 +76,18 @@ void
 dump_class (progs_t *pr, pr_class_t *class)
 {
 	pr_class_t *meta = &G_STRUCT (pr, pr_class_t, class->class_pointer);
+	const char *class_name = "<invalid string>";
+	const char *super_class_name = "<invalid string>";
 
+	if (PR_StringValid (pr, class->name))
+		class_name = PR_GetString (pr, class->name);
 	if (class->super_class) {
-		printf ("    %s @ %d : %s\n", PR_GetString (pr, class->name),
-				POINTER_TO_PROG (pr, class), PR_GetString (pr,
-														   class->super_class));
+		if (PR_StringValid (pr, class->super_class))
+			class_name = PR_GetString (pr, class->super_class);
+		printf ("    %s @ %d : %s\n", class_name, POINTER_TO_PROG (pr, class),
+				super_class_name);
 	} else {
-		printf ("    %s @ %d\n", PR_GetString (pr, class->name),
-				POINTER_TO_PROG (pr, class));
+		printf ("    %s @ %d\n", class_name, POINTER_TO_PROG (pr, class));
 	}
 	printf ("        %d %d %d %d\n", class->class_pointer, class->version,
 			class->info, class->instance_size);
@@ -98,9 +106,11 @@ dump_module (progs_t *pr, pr_module_t *module)
 	pr_symtab_t *symtab = &G_STRUCT (pr, pr_symtab_t, module->symtab);
 	pointer_t  *ptr = symtab->defs;
 	int         i;
+	const char *module_name = "<invalid string>";
 
-	printf ("%d %d %s\n", module->version, module->size,
-			PR_GetString (pr, module->name));
+	if (PR_StringValid (pr, module->name))
+		module_name = PR_GetString (pr, module->name);
+	printf ("%d %d %s\n", module->version, module->size, module_name);
 	if (!symtab) {
 		printf ("    No symtab!\n");
 		return;
@@ -117,12 +127,13 @@ void
 dump_modules (progs_t *pr)
 {
 	int i;
-	const char *name;
 
 	for (i = 0; i < pr->progs->numglobaldefs; i++) {
-		ddef_t *def = &pr->pr_globaldefs[i];
+		ddef_t     *def = &pr->pr_globaldefs[i];
+		const char *name = "<invalid_string>";
 
-		name = PR_GetString (pr, def->s_name);
+		if (PR_StringValid (pr, def->s_name))
+			name = PR_GetString (pr, def->s_name);
 		if (strcmp (name, "_OBJ_MODULE") == 0)
 			dump_module (pr, &G_STRUCT (pr, pr_module_t, def->ofs));
 	}