diff --git a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/EDL.xtext b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/EDL.xtext
index fa2a41810..34d73ba89 100644
--- a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/EDL.xtext
+++ b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/EDL.xtext
@@ -33,7 +33,7 @@ DataContractDefinition returns DataContractDefinition:
 ;	
 
 FieldDeclaration returns FieldDeclaration:
-	name=ID ":" type=QualifiedName
+	name=ID ":" type=TypeName
 ;
 
 
@@ -55,7 +55,7 @@ AliasDefinition returns AliasDefinition:
 ;
 
 IdDefinition returns IdDefinition:
-	fieldName=EString ':' type = QualifiedName  (isAssigned?= ':=' value = Query)?
+	fieldName=EString ':' type = TypeName  (isAssigned?= ':=' value = Query)?
 ;
 
 ExchangeRule returns ExchangeRule:
@@ -68,6 +68,10 @@ QualifiedName returns QualifiedName:
 	name=ID
 ;
 
+TypeName returns QualifiedName:
+	name = ("int" | "float" | "string" | "bool") | QualifiedName
+;
+
 
 // ===== Core types (terminals) =====
 
diff --git a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/generator/EDLGenerator.xtend b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/generator/EDLGenerator.xtend
index c0f95c417..f6cfe8dc2 100644
--- a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/generator/EDLGenerator.xtend
+++ b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/generator/EDLGenerator.xtend
@@ -43,9 +43,9 @@ import java.util.List;
 import cz.cuni.mff.d3s.deeco.ensembles.EnsembleInstance;
 
 public class «e.name» implements EnsembleInstance {
-	public «e.id.type.name» «e.id.fieldName»;
+	public «getJavaTypeName(e.id.type.name)» «e.id.fieldName»;
 	
-	public «e.name»(«e.id.type.name» «e.id.fieldName») {
+	public «e.name»(«getJavaTypeName(e.id.type.name)» «e.id.fieldName») {
 		this.«e.id.fieldName» = «e.id.fieldName»;
 		«FOR r : e.roles»
 		«IF r.cardinalityMax != 1»		
@@ -77,10 +77,17 @@ public class «e.name» implements EnsembleInstance {
 
 public class «d.name» {	
 	«FOR f : d.fields»				
-	public «f.type.name» «f.name»;				
+	public «getJavaTypeName(f.type.name)» «f.name»;				
 	«ENDFOR»				
 }'''
 			);
 	}
 	
+	def String getJavaTypeName(String type) {
+		if (type.equals("string"))
+			"String"
+		else
+			type
+	}
+	
 }
diff --git a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/validation/EDLValidator.xtend b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/validation/EDLValidator.xtend
index 7d45f6456..e9511d5bd 100644
--- a/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/validation/EDLValidator.xtend
+++ b/jdeeco-edl/src/cz/cuni/mff/d3s/jdeeco/edl/validation/EDLValidator.xtend
@@ -64,7 +64,7 @@ class EDLValidator extends AbstractEDLValidator {
 	}
 	
 	@Check
-	def validateEnsembleTypeInformation(EnsembleDefinition ensemble) {
+	def validateEnsembleDefinition(EnsembleDefinition ensemble) {
 		if (ensemble.fitness != null) {
 			val type = checkTypes(ensemble.fitness, ensemble)
 			if (!type.equals("int"))
@@ -72,7 +72,11 @@ class EDLValidator extends AbstractEDLValidator {
 		}
 		
 		for (Query c : ensemble.constraints) {
-			checkTypes(c, ensemble)
+			val type = checkTypes(c, ensemble)
+			// TODO: Improve model so the constraint errors can be reported per constraint
+//			if (!type.equals("bool")) {
+//				error("Constraint must be a logical expression. - " + type, ensemble, EdlPackage.Literals.ENSEMBLE_DEFINITION__CONSTRAINTS)
+//			}
 		}	
 		
 		for (AliasDefinition a : ensemble.aliases) {