diff --git a/prism/src/prism/PrismSettings.java b/prism/src/prism/PrismSettings.java
index 618ce634..9a8270b7 100644
--- a/prism/src/prism/PrismSettings.java
+++ b/prism/src/prism/PrismSettings.java
@@ -311,7 +311,7 @@ public class PrismSettings implements Observer
 			{ STRING_TYPE,		PRISM_LTL2DA_TOOL,						"Use external LTL->DA tool",		"4.2.1",			"",		null,
 																			"If non-empty, the path to the executable for the external LTL->DA tool."},
 
-			{ STRING_TYPE,		PRISM_LTL2DA_SYNTAX,					"LTL syntax for external LTL->DA tool",		"4.2.1",			"LBT",		"LBT,Spin,Spot,Rabinizer",
+			{ CHOICE_TYPE,		PRISM_LTL2DA_SYNTAX,					"LTL syntax for external LTL->DA tool",		"4.2.1",			"LBT",		"LBT,Spin,Spot,Rabinizer",
 																			"The syntax for LTL formulas passed to the external LTL->DA tool."},
 
 			// PARAMETRIC MODEL CHECKING