diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/FilterCompiler.java b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/FilterCompiler.java
index 819dbe12..4dd670a2 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/FilterCompiler.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/FilterCompiler.java
@@ -85,6 +85,9 @@ public class FilterCompiler {
                     filter.incrementPosition(1);
                     ExpressionNode expressionNode = expStack.pop();
                     if(!opsStack.isEmpty()){
+                        if(expStack.isEmpty()){
+                            throw new InvalidPathException("Expected expression on right hand side of operator");
+                        }
                         ExpressionNode right = expStack.pop();
                         expressionNode = ExpressionNode.createExpressionNode(expressionNode, opsStack.pop(), right);
                         while(!opsStack.isEmpty()){
@@ -110,7 +113,7 @@ public class FilterCompiler {
                 throw new InvalidPathException("Failed to parse filter " + filter.toString());
             }
         }
-        if(unbalancedBrackets > 0){
+        if(unbalancedBrackets != 0){
             throw new InvalidPathException("Failed to parse filter. Brackets are not balanced. " + filter.toString());
         }
 
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/RelationalOperator.java b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/RelationalOperator.java
index d3ebbc36..c5051344 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/RelationalOperator.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/RelationalOperator.java
@@ -33,7 +33,7 @@ public enum RelationalOperator {
                 return operator;
             }
         }
-        throw new InvalidPathException("Operator not supported " + operatorString);
+        throw new InvalidPathException("Operator " + operatorString + " not supported ");
     }
 
     @Override
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/ValueNode.java b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/ValueNode.java
index ddbb3796..7e53868c 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/filter/ValueNode.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/filter/ValueNode.java
@@ -239,9 +239,6 @@ public abstract class ValueNode {
             this.compiledPattern = pattern;
         }
 
-        public String getPattern() {
-            return "/" + pattern + "/";
-        }
 
         public Pattern getCompiledPattern() {
             return compiledPattern;
@@ -262,7 +259,15 @@ public abstract class ValueNode {
 
         @Override
         public String toString() {
-            return pattern;
+
+            String flags = "";
+            if((compiledPattern.flags() & Pattern.CASE_INSENSITIVE) == Pattern.CASE_INSENSITIVE){
+                flags = "i";
+            }
+
+
+
+            return "/" + pattern + "/" + flags;
         }
 
         @Override
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/function/numeric/AbstractAggregation.java b/json-path/src/main/java/com/jayway/jsonpath/internal/function/numeric/AbstractAggregation.java
index e23d945f..e6e409f2 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/function/numeric/AbstractAggregation.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/function/numeric/AbstractAggregation.java
@@ -35,11 +35,6 @@ public abstract class AbstractAggregation implements Function {
 
             Iterable<?> objects = ctx.configuration().jsonProvider().toIterable(model);
             for (Object obj : objects) {
-//                Object unwraped = ctx.configuration().jsonProvider().unwrap(obj);
-//                if (unwraped instanceof Number) {
-//                    Number value = (Number) unwraped;
-//                    next(value);
-//                }
                 if (obj instanceof Number) {
                     Number value = (Number) obj;
                     next(value);
diff --git a/json-path/src/test/java/com/jayway/jsonpath/FilterCompilerTest.java b/json-path/src/test/java/com/jayway/jsonpath/FilterCompilerTest.java
index b95dea9d..06925af0 100644
--- a/json-path/src/test/java/com/jayway/jsonpath/FilterCompilerTest.java
+++ b/json-path/src/test/java/com/jayway/jsonpath/FilterCompilerTest.java
@@ -9,7 +9,7 @@ public class FilterCompilerTest {
 
 
     @Test
-    public void filter_compiler_test() {
+    public void valid_filters_compile() {
         assertThat(compile("[?(@)]").toString()).isEqualTo("[?(@)]");
         assertThat(compile("[?(@)]").toString()).isEqualTo("[?(@)]");
         assertThat(compile("[?(@.firstname)]").toString()).isEqualTo("[?(@['firstname'])]");
@@ -40,5 +40,28 @@ public class FilterCompilerTest {
         assertThat(compile("[?(@.message.%min()==10)]").toString()).isEqualTo("[?(@['message'].%min() == 10)]");
         assertThat(compile("[?(10 == @.message.%min())]").toString()).isEqualTo("[?(10 == @['message'].%min())]");
         assertThat(compile("[?(((@)))]").toString()).isEqualTo("[?(@)]");
+        assertThat(compile("[?(@.name =~ /.*?/i)]").toString()).isEqualTo("[?(@['name'] =~ /.*?/i)]");
+        assertThat(compile("[?(@.name =~ /.*?/)]").toString()).isEqualTo("[?(@['name'] =~ /.*?/)]");
+
+    }
+
+
+    @Test
+    public void invalid_filters_does_not_compile() {
+        assertInvalidPathException("[?(@))]");
+        assertInvalidPathException("[?(@ FOO 1)]");
+        assertInvalidPathException("[?(@ || )]");
+        assertInvalidPathException("[?(@ == 'foo )]");
+        assertInvalidPathException("[?(@ == 1' )]");
+    }
+
+
+    private void assertInvalidPathException(String filter){
+        try {
+            compile(filter);
+            throw new AssertionError("Expected " + filter + " to throw InvalidPathException");
+        } catch (InvalidPathException e){
+            e.printStackTrace();
+        }
     }
 }