diff --git a/driver/src/main/java/com/consol/citrus/db/driver/statement/StatementComposer.java b/driver/src/main/java/com/consol/citrus/db/driver/statement/StatementComposer.java
index c9650f0..9225c4c 100644
--- a/driver/src/main/java/com/consol/citrus/db/driver/statement/StatementComposer.java
+++ b/driver/src/main/java/com/consol/citrus/db/driver/statement/StatementComposer.java
@@ -39,18 +39,16 @@ private Collection<Object> determineParameterOrder(final String statement,
             The intended group to catch is the group of variables in the sql statement.
             In case of a callable statement, it is possible that the statement starts with a '? = '
             indicating a out parameter of the statement. This parameter should be ignored concerning variable
-            replacement. That is why the first group catches the '? = ' (if existing) and the second group catches
+            replacement. That is why the first non-catching group handles the '? = ' (if existing) and the second group catches
             named and unnamed variable references within the rest of the sql statement.
-            This is why the first group should be ignored due variable substitution while the second group contains all
-            variables to replace
          */
-        final Pattern parameterPattern = Pattern.compile("^(\\? ?=)+|(:[a-zA-Z]+|\\?)");
+        final Pattern parameterPattern = Pattern.compile("(?:\\? ?=)|(:[a-zA-Z]+|\\?)");
         final Matcher parameterMatcher = parameterPattern.matcher(statement);
 
         final LinkedList<Object> orderedParameterList = new LinkedList<>();
 
         for(int matchIndex = 1; parameterMatcher.find(); matchIndex++){
-            final String parameterPlaceholder = parameterMatcher.group(2);
+            final String parameterPlaceholder = parameterMatcher.group(1);
             if(parameterPlaceholder != null) {
                 orderedParameterList.add(
                         getParameterValue(parameters, parameterPlaceholder, matchIndex));
@@ -76,4 +74,4 @@ private Object getParameterValue(final StatementParameters parameters,
             return parameterPlaceholder;
         }
     }
-}
+}
\ No newline at end of file
diff --git a/driver/src/test/java/com/consol/citrus/db/driver/statement/StatementComposerTest.java b/driver/src/test/java/com/consol/citrus/db/driver/statement/StatementComposerTest.java
index 9b2bb5c..10d90e9 100644
--- a/driver/src/test/java/com/consol/citrus/db/driver/statement/StatementComposerTest.java
+++ b/driver/src/test/java/com/consol/citrus/db/driver/statement/StatementComposerTest.java
@@ -113,11 +113,13 @@ public void testCallableStatementParameterAreReplacedCorrectly(){
     public void testReturnValuesOfCallableStatementsAreParsedCorrectly(){
 
         //GIVEN
-        final String statement = "? = CALL someFunction(?)";
-        final String expectedComposedStatement = statement + " - (?)";
+        final String statement = "{? = CALL someFunction(?)}";
+        final StatementParameters statementParameters = new StatementParameters();
+        statementParameters.setParameter(2, "foobar");
+        final String expectedComposedStatement = statement + " - (foobar)";
 
         //WHEN
-        final String composedStatement = statementComposer.composeStatement(statement, new StatementParameters());
+        final String composedStatement = statementComposer.composeStatement(statement, statementParameters);
 
         //THEN
         assertEquals(composedStatement, expectedComposedStatement);