diff --git a/java/pom.xml b/java/pom.xml
index 09b0aa7..18de6a7 100644
--- a/java/pom.xml
+++ b/java/pom.xml
@@ -11,7 +11,7 @@
 
     <groupId>io.github.universal-variability-language</groupId>
     <artifactId>uvl-parser</artifactId>
-    <version>0.4</version>
+    <version>0.4.1</version>
 
     <licenses>
         <license>
diff --git a/uvl/UVLLexer.g4 b/uvl/UVLLexer.g4
index d308e8a..8013bd4 100644
--- a/uvl/UVLLexer.g4
+++ b/uvl/UVLLexer.g4
@@ -8,6 +8,7 @@ FEATURES_KEY: 'features';
 IMPORTS_KEY: 'imports';
 NAMESPACE_KEY: 'namespace';
 AS_KEY: 'as';
+CONSTRAINT_KEY: 'constraint';
 CONSTRAINTS_KEY: 'constraints';
 CARDINALITY_KEY: 'cardinality';
 STRING_KEY: 'String';
@@ -60,17 +61,17 @@ CLOSE_BRACE: '}';
 OPEN_COMMENT: '/*';
 CLOSE_COMMENT: '*/';
 
-FLOAT: '-'? [0-9]* [.][0-9]+;
-INTEGER: '0' | '-'? [1-9][0-9]*;
+FLOAT: '-'?[0-9]*[.][0-9]+;
+INTEGER: '0' | '-'?[1-9][0-9]*;
 BOOLEAN: 'true' | 'false';
 
 COMMA: ',';
 DOT: '.';
 
-ID_NOT_STRICT: '"' ~[\r\n".]+ '"';
+ID_NOT_STRICT: '"'~[\r\n".]+'"';
 ID_STRICT: [a-zA-Z]([a-zA-Z0-9_#§%?\\'äüöß;])*;
 
-STRING: '\'' ~[\r\n']+ '\'';
+STRING: '\''~[\r\n']+'\'';
 
 SKIP_: ( SPACES | COMMENT) -> skip;
 
diff --git a/uvl/UVLParser.g4 b/uvl/UVLParser.g4
index 831d380..528ca6a 100644
--- a/uvl/UVLParser.g4
+++ b/uvl/UVLParser.g4
@@ -44,7 +44,7 @@ value: BOOLEAN | FLOAT | INTEGER | STRING | attributes | vector;
 vector: OPEN_BRACK (value (COMMA value)*)? CLOSE_BRACK;
 
 constraintAttribute:
-	CONSTRAINTS_KEY constraint			# SingleConstraintAttribute
+	CONSTRAINT_KEY constraint			# SingleConstraintAttribute
 	| CONSTRAINTS_KEY constraintList	# ListConstraintAttribute;
 constraintList:
 	OPEN_BRACK (constraint (COMMA constraint)*)? CLOSE_BRACK;