diff --git a/src/fp/fp0700.cpp b/src/fp/fp0700.cpp
index dbb8eb7f4..5179cb8ca 100644
--- a/src/fp/fp0700.cpp
+++ b/src/fp/fp0700.cpp
@@ -528,7 +528,7 @@ bool TPAR_mask::on_field_event(TOperable_field& o, TField_event e, long jolly)
 {
 	const bool diagn = get_bool(F_DIAGN);
 	TString filter_selected = get(F_REGSEL);
-	bool ok;
+	bool ok = true;
 
 	switch (o.dlg())
 	{