diff --git a/prism/src/parser/ast/ConstantList.java b/prism/src/parser/ast/ConstantList.java
index 2cfe6ed5..57f097fd 100644
--- a/prism/src/parser/ast/ConstantList.java
+++ b/prism/src/parser/ast/ConstantList.java
@@ -32,8 +32,10 @@ import parser.*;
 import parser.visitor.*;
 import prism.PrismLangException;
 import parser.type.*;
-// class to store list of constants
 
+/**
+ * Class to store list of (defined and undefined) constants
+ */
 public class ConstantList extends ASTElement
 {
 	// Name/expression/type triples to define constants
@@ -173,8 +175,9 @@ public class ConstantList extends ASTElement
 		}
 	}
 	
-	// get number of undefined constants
-	
+	/**
+	 * Get the number of undefined constants in the list.
+	 */
 	public int getNumUndefined()
 	{
 		int i, n, res;
@@ -192,8 +195,9 @@ public class ConstantList extends ASTElement
 		return res;
 	}
 	
-	// get undefined constants
-	
+	/**
+	 * Get a list of the undefined constants in the list.
+	 */
 	public Vector<String> getUndefinedConstants()
 	{
 		int i, n;
@@ -212,6 +216,18 @@ public class ConstantList extends ASTElement
 		return v;
 	}
 	
+	/**
+	 * Check if {@code name} is a *defined* constants in the list,
+	 * i.e. a constant whose value was *not* left unspecified in the model/property.
+	 */
+	public boolean isDefinedConstant(String name)
+	{
+		int i = getConstantIndex(name);
+		if (i == -1)
+			return false;
+		return (getConstant(i) != null);
+	}
+	
 	/**
 	 * Set values for *all* undefined constants, evaluate values for *all* constants
 	 * and return a Values object with values for *all* constants.
diff --git a/prism/src/parser/ast/ModulesFile.java b/prism/src/parser/ast/ModulesFile.java
index 4f9a069e..ac51e38f 100644
--- a/prism/src/parser/ast/ModulesFile.java
+++ b/prism/src/parser/ast/ModulesFile.java
@@ -771,6 +771,15 @@ public class ModulesFile extends ASTElement
 		semanticCheckAfterConstants(this, null);
 	}
 
+	/**
+	 * Check if {@code name} is a *defined* constant in the model,
+	 * i.e. a constant whose value was *not* left unspecified.
+	 */
+	public boolean isDefinedConstant(String name)
+	{
+		return constantList.isDefinedConstant(name);
+	}
+	
 	/**
 	 * Get access to the values for all constants in the model, including the 
 	 * undefined constants set previously via the method {@link #setUndefinedConstants(Values)}.
diff --git a/prism/src/parser/ast/PropertiesFile.java b/prism/src/parser/ast/PropertiesFile.java
index 4472af18..1a14d8e3 100644
--- a/prism/src/parser/ast/PropertiesFile.java
+++ b/prism/src/parser/ast/PropertiesFile.java
@@ -447,6 +447,15 @@ public class PropertiesFile extends ASTElement
 		// (and sometimes we don't want to have to define all constants)
 	}
 	
+	/**
+	 * Check if {@code name} is a *defined* constant in the properties file,
+	 * i.e. a constant whose value was *not* left unspecified.
+	 */
+	public boolean isDefinedConstant(String name)
+	{
+		return constantList.isDefinedConstant(name);
+	}
+	
 	/**
 	 * Get access to the values for all constants in the properties file, including the
 	 * undefined constants set previously via the method {@link #setUndefinedConstants(Values)}