diff --git a/prism/src/prism/NonProbModelChecker.java b/prism/src/prism/NonProbModelChecker.java
new file mode 100644
index 00000000..7577aaf8
--- /dev/null
+++ b/prism/src/prism/NonProbModelChecker.java
@@ -0,0 +1,95 @@
+//==============================================================================
+//	
+//	Copyright (c) 2002-
+//	Authors:
+//	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
+//	
+//------------------------------------------------------------------------------
+//	
+//	This file is part of PRISM.
+//	
+//	PRISM is free software; you can redistribute it and/or modify
+//	it under the terms of the GNU General Public License as published by
+//	the Free Software Foundation; either version 2 of the License, or
+//	(at your option) any later version.
+//	
+//	PRISM is distributed in the hope that it will be useful,
+//	but WITHOUT ANY WARRANTY; without even the implied warranty of
+//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//	GNU General Public License for more details.
+//	
+//	You should have received a copy of the GNU General Public License
+//	along with PRISM; if not, write to the Free Software Foundation,
+//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//	
+//==============================================================================
+
+package prism;
+
+import jdd.*;
+import parser.ast.*;
+
+/*
+ * Non probabilistic model checker, initially for CTL.
+ */
+public class NonProbModelChecker extends StateModelChecker
+{
+	// Constructor
+
+	public NonProbModelChecker(Prism prism, Model m, PropertiesFile pf) throws PrismException
+	{
+		// Initialise
+		super(prism, m, pf);
+	}
+
+	// -----------------------------------------------------------------------------------
+	// Check a property, i.e. an expression
+	// -----------------------------------------------------------------------------------
+
+	// Check expression (recursive)
+
+	public StateProbs checkExpression(Expression expr) throws PrismException
+	{
+		StateProbs res;
+
+		// E operator
+		if (expr instanceof ExpressionExists) {
+			res = checkExpressionExists(((ExpressionExists) expr).getExpression());
+		}
+		// A operator
+		if (expr instanceof ExpressionForAll) {
+			res = checkExpressionForAll(((ExpressionForAll) expr).getExpression());
+		}
+		// Otherwise, use the superclass
+		else {
+			res = super.checkExpression(expr);
+		}
+
+		// Filter out non-reachable states from solution
+		// (only necessary for symbolically stored vectors)
+		if (res instanceof StateProbsMTBDD)
+			res.filter(reach);
+
+		return res;
+	}
+
+	// -----------------------------------------------------------------------------------
+	// Check method for each operator
+	// -----------------------------------------------------------------------------------
+
+	// E operator
+
+	protected StateProbs checkExpressionExists(Expression expr) throws PrismException
+	{
+		throw new PrismException("CTL model checking is not yet supported");
+	}
+	
+	// A operator
+
+	protected StateProbs checkExpressionForAll(Expression expr) throws PrismException
+	{
+		throw new PrismException("CTL model checking is not yet supported");
+	}
+}
+
+// ------------------------------------------------------------------------------
diff --git a/prism/src/prism/ProbModelChecker.java b/prism/src/prism/ProbModelChecker.java
index 5e8482c1..876910ce 100644
--- a/prism/src/prism/ProbModelChecker.java
+++ b/prism/src/prism/ProbModelChecker.java
@@ -38,7 +38,7 @@ import parser.ast.*;
 /*
  * Model checker for DTMCs.
  */
-public class ProbModelChecker extends StateModelChecker
+public class ProbModelChecker extends NonProbModelChecker
 {
 	// SCC computer
 	protected SCCComputer sccComputer;