diff --git a/ph-schematron-pure/src/main/java/com/helger/schematron/pure/bound/xpath/PSXPathBoundSchema.java b/ph-schematron-pure/src/main/java/com/helger/schematron/pure/bound/xpath/PSXPathBoundSchema.java
index f749f0ab7..07a60b2e1 100644
--- a/ph-schematron-pure/src/main/java/com/helger/schematron/pure/bound/xpath/PSXPathBoundSchema.java
+++ b/ph-schematron-pure/src/main/java/com/helger/schematron/pure/bound/xpath/PSXPathBoundSchema.java
@@ -569,15 +569,11 @@ private void _evaluateVariables (@Nonnull final PSXPathVariables aVariables,
 
       Object aEvalResult;
 
-      // We don't know the type returned by the XPath expression, so we try
-      // them one after another
-      // Based on some common cases, the chances for "NodeList" results and
-      // "String" results are highest, so they are tried first
-
+      // First we try type auto detection magic, that only works if Saxon is on
+      // the classpath. See #170 for the original intention
       try
       {
-        aEvalResult = XPathEvaluationHelper.evaluateAsNodeList (aXPathExpression, aNode, sBaseURI);
-        m_nVarForNodeLists++;
+        aEvalResult = XPathEvaluationHelper.evaluateWithTypeAutodetect (aXPathExpression, aNode, sBaseURI);
       }
       catch (final XPathExpressionException ex)
       {
@@ -585,6 +581,22 @@ private void _evaluateVariables (@Nonnull final PSXPathVariables aVariables,
         aEvalResult = null;
       }
 
+      // We don't know the type returned by the XPath expression, so we try
+      // them one after another
+      // Based on some common cases, the chances for "NodeList" results and
+      // "String" results are highest, so they are tried first
+
+      if (aEvalResult == null)
+        try
+        {
+          aEvalResult = XPathEvaluationHelper.evaluateAsNodeList (aXPathExpression, aNode, sBaseURI);
+          m_nVarForNodeLists++;
+        }
+        catch (final XPathExpressionException ex)
+        {
+          // ignore
+        }
+
       // Number first, so that e.g. "sum()" is evaluated as a Number
       // Numbers can be converted to boolean and to string
       if (aEvalResult == null)
diff --git a/ph-schematron-pure/src/main/java/com/helger/schematron/pure/xpath/XPathEvaluationHelper.java b/ph-schematron-pure/src/main/java/com/helger/schematron/pure/xpath/XPathEvaluationHelper.java
index 90120a6b6..ff3dac7aa 100644
--- a/ph-schematron-pure/src/main/java/com/helger/schematron/pure/xpath/XPathEvaluationHelper.java
+++ b/ph-schematron-pure/src/main/java/com/helger/schematron/pure/xpath/XPathEvaluationHelper.java
@@ -24,6 +24,8 @@
 import javax.xml.xpath.XPathExpression;
 import javax.xml.xpath.XPathExpressionException;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
@@ -31,6 +33,27 @@
 import com.helger.xml.XMLHelper;
 
 import net.sf.saxon.dom.DocumentWrapper;
+import net.sf.saxon.expr.ArithmeticExpression;
+import net.sf.saxon.expr.CastExpression;
+import net.sf.saxon.expr.ContextItemExpression;
+import net.sf.saxon.expr.Expression;
+import net.sf.saxon.expr.FirstItemExpression;
+import net.sf.saxon.expr.GeneralComparison;
+import net.sf.saxon.expr.Literal;
+import net.sf.saxon.expr.SlashExpression;
+import net.sf.saxon.expr.StaticFunctionCall;
+import net.sf.saxon.expr.StringLiteral;
+import net.sf.saxon.expr.ValueComparison;
+import net.sf.saxon.expr.sort.DocumentSorter;
+import net.sf.saxon.om.FunctionItem;
+import net.sf.saxon.type.AtomicType;
+import net.sf.saxon.type.BuiltInAtomicType;
+import net.sf.saxon.type.ItemType;
+import net.sf.saxon.value.BigDecimalValue;
+import net.sf.saxon.value.BooleanValue;
+import net.sf.saxon.value.Int64Value;
+import net.sf.saxon.value.SequenceExtent;
+import net.sf.saxon.xpath.JAXPVariableReference;
 import net.sf.saxon.xpath.XPathExpressionImpl;
 
 /**
@@ -42,23 +65,148 @@
 @Immutable
 public final class XPathEvaluationHelper
 {
+  // Separate class that only gets loaded if Saxon is on the classpath
+  @Immutable
+  private static final class SaxonEvaluator
+  {
+    private static final Logger LOGGER = LoggerFactory.getLogger (SaxonEvaluator.class);
+
+    private SaxonEvaluator ()
+    {}
+
+    @Nonnull
+    static Object getBaseUriFixed (@Nonnull final XPathExpression aXPath,
+                                   @Nonnull final Node aNode,
+                                   @Nonnull final String sBaseURI)
+    {
+      // Saxon specific handling
+      // This is trick needed for #47 - "base-uri()"
+      final XPathExpressionImpl aImpl = (XPathExpressionImpl) aXPath;
+      return new DocumentWrapper (XMLHelper.getOwnerDocument (aNode), sBaseURI, aImpl.getConfiguration ()).wrap (aNode);
+    }
+
+    @Nullable
+    private static QName _findReturnType (@Nonnull final ItemType type)
+    {
+      if (type instanceof BuiltInAtomicType)
+      {
+        final BuiltInAtomicType biat = (BuiltInAtomicType) type;
+        if (biat.equals (BuiltInAtomicType.BOOLEAN))
+          return XPathConstants.BOOLEAN;
+        if (biat.isNumericType ())
+          return XPathConstants.NUMBER;
+        if (BuiltInAtomicType.isStringLike (biat))
+          return XPathConstants.STRING;
+        // Fall back to node set
+        return XPathConstants.NODESET;
+      }
+      LOGGER.warn ("Unknown Saxon type: " + (type == null ? "null" : type.getClass ().getName ()));
+      return null;
+    }
+
+    @Nullable
+    private static QName _findReturnType (@Nonnull final Expression expr)
+    {
+      if (expr instanceof ValueComparison || expr instanceof GeneralComparison)
+        return XPathConstants.BOOLEAN;
+      if (expr instanceof StringLiteral)
+        return XPathConstants.STRING;
+      if (expr instanceof ArithmeticExpression)
+        return XPathConstants.NUMBER;
+      if (expr instanceof ContextItemExpression || expr instanceof FirstItemExpression)
+        return XPathConstants.NODE;
+      if (expr instanceof SlashExpression || expr instanceof DocumentSorter)
+        return XPathConstants.NODESET;
+      if (expr instanceof Literal)
+      {
+        final Literal lit = (Literal) expr;
+        final var litValue = lit.getGroundedValue ();
+        if (litValue instanceof BooleanValue)
+          return XPathConstants.BOOLEAN;
+        if (litValue instanceof BigDecimalValue || litValue instanceof Int64Value)
+          return XPathConstants.NUMBER;
+        if (litValue instanceof SequenceExtent.Of)
+          return XPathConstants.NODESET;
+        LOGGER.warn ("Unknown Saxon grounded value type: " +
+                     (litValue == null ? "null" : litValue.getClass ().getName ()));
+        return null;
+      }
+      if (expr instanceof CastExpression)
+      {
+        final AtomicType aTargetType = ((CastExpression) expr).getTargetType ();
+        return _findReturnType (aTargetType);
+      }
+      if (expr instanceof StaticFunctionCall)
+      {
+        final FunctionItem aTargetFun = ((StaticFunctionCall) expr).getTargetFunction ();
+        return _findReturnType (aTargetFun.getFunctionItemType ().getResultType ().getPrimaryType ());
+      }
+      if (expr instanceof JAXPVariableReference)
+      {
+        // As it is unclear, if the variable can be resolved at all, we just
+        // skip this
+        return null;
+      }
+
+      LOGGER.warn ("Unknown Saxon expression type: " + expr.getClass ().getName ());
+      return null;
+    }
+
+    @Nullable
+    static QName findReturnType (@Nonnull final XPathExpression aXPath)
+    {
+      final XPathExpressionImpl aImpl = (XPathExpressionImpl) aXPath;
+      try
+      {
+        // tested with Saxon 12.5
+        return _findReturnType (aImpl.getInternalExpression ());
+      }
+      catch (final Throwable ex)
+      {
+        // E.g. method not found, type not found etc. Just a catch all
+        LOGGER.error ("Failed to evaluate Saxon internal type: " +
+                      ex.getClass ().getName () +
+                      " - " +
+                      ex.getMessage ());
+        return null;
+      }
+    }
+  }
+
   private XPathEvaluationHelper ()
   {}
 
+  private static boolean isSaxonImplementation (@Nonnull final XPathExpression aXPath)
+  {
+    return "net.sf.saxon.xpath.XPathExpressionImpl".equals (aXPath.getClass ().getName ());
+  }
+
+  @Nullable
+  public static Object evaluateWithTypeAutodetect (@Nonnull final XPathExpression aXPath,
+                                                   @Nonnull final Node aNode,
+                                                   @Nullable final String sBaseURI) throws XPathExpressionException
+  {
+    if (!isSaxonImplementation (aXPath))
+      return null;
+
+    // Saxon specific magic
+    final QName aReturnType = SaxonEvaluator.findReturnType (aXPath);
+    if (aReturnType == null)
+      return null;
+
+    return evaluate (aXPath, aNode, aReturnType, sBaseURI);
+  }
+
   @Nullable
   public static <T> T evaluate (@Nonnull final XPathExpression aXPath,
-                                @Nonnull final Node aItem,
+                                @Nonnull final Node aNode,
                                 @Nonnull final QName aReturnType,
                                 @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    Object aRealItem = aItem;
-    if (sBaseURI != null && "net.sf.saxon.xpath.XPathExpressionImpl".equals (aXPath.getClass ().getName ()))
+    Object aRealItem = aNode;
+    if (sBaseURI != null && isSaxonImplementation (aXPath))
     {
-      // Saxon specific handling
-      // This is trick needed for #47 - "base-uri()"
-      final XPathExpressionImpl aImpl = (XPathExpressionImpl) aXPath;
-      aRealItem = new DocumentWrapper (XMLHelper.getOwnerDocument (aItem), sBaseURI, aImpl.getConfiguration ()).wrap (
-                                                                                                                      aItem);
+      aRealItem = SaxonEvaluator.getBaseUriFixed (aXPath, aNode, sBaseURI);
     }
 
     // Unfortunately there is no "any" type
@@ -68,17 +216,17 @@ public static <T> T evaluate (@Nonnull final XPathExpression aXPath,
 
   @Nullable
   public static Boolean evaluateAsBooleanObj (@Nonnull final XPathExpression aXPath,
-                                              @Nonnull final Node aItem,
+                                              @Nonnull final Node aNode,
                                               @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    return evaluate (aXPath, aItem, XPathConstants.BOOLEAN, sBaseURI);
+    return evaluate (aXPath, aNode, XPathConstants.BOOLEAN, sBaseURI);
   }
 
   public static boolean evaluateAsBoolean (@Nonnull final XPathExpression aXPath,
-                                           @Nonnull final Node aItem,
+                                           @Nonnull final Node aNode,
                                            @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    final Boolean aVal = evaluateAsBooleanObj (aXPath, aItem, sBaseURI);
+    final Boolean aVal = evaluateAsBooleanObj (aXPath, aNode, sBaseURI);
     if (aVal == null)
       throw new XPathExpressionException ("Failed to evaluate the XPath expression as boolean");
     return aVal.booleanValue ();
@@ -86,33 +234,33 @@ public static boolean evaluateAsBoolean (@Nonnull final XPathExpression aXPath,
 
   @Nullable
   public static Node evaluateAsNode (@Nonnull final XPathExpression aXPath,
-                                     @Nonnull final Node aItem,
+                                     @Nonnull final Node aNode,
                                      @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    return evaluate (aXPath, aItem, XPathConstants.NODE, sBaseURI);
+    return evaluate (aXPath, aNode, XPathConstants.NODE, sBaseURI);
   }
 
   @Nullable
   public static NodeList evaluateAsNodeList (@Nonnull final XPathExpression aXPath,
-                                             @Nonnull final Node aItem,
+                                             @Nonnull final Node aNode,
                                              @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    return evaluate (aXPath, aItem, XPathConstants.NODESET, sBaseURI);
+    return evaluate (aXPath, aNode, XPathConstants.NODESET, sBaseURI);
   }
 
   @Nullable
   public static Double evaluateAsNumber (@Nonnull final XPathExpression aXPath,
-                                         @Nonnull final Node aItem,
+                                         @Nonnull final Node aNode,
                                          @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    return evaluate (aXPath, aItem, XPathConstants.NUMBER, sBaseURI);
+    return evaluate (aXPath, aNode, XPathConstants.NUMBER, sBaseURI);
   }
 
   @Nullable
   public static String evaluateAsString (@Nonnull final XPathExpression aXPath,
-                                         @Nonnull final Node aItem,
+                                         @Nonnull final Node aNode,
                                          @Nullable final String sBaseURI) throws XPathExpressionException
   {
-    return evaluate (aXPath, aItem, XPathConstants.STRING, sBaseURI);
+    return evaluate (aXPath, aNode, XPathConstants.STRING, sBaseURI);
   }
 }
diff --git a/ph-schematron-pure/src/test/java/com/helger/schematron/pure/supplementary/Issue170Test.java b/ph-schematron-pure/src/test/java/com/helger/schematron/pure/supplementary/Issue170Test.java
index 59cb64518..4dcb35482 100644
--- a/ph-schematron-pure/src/test/java/com/helger/schematron/pure/supplementary/Issue170Test.java
+++ b/ph-schematron-pure/src/test/java/com/helger/schematron/pure/supplementary/Issue170Test.java
@@ -46,10 +46,10 @@ public static void validateAndProduceSVRL (@Nonnull final File aSchematron, fina
     // Perform validation
     final SchematronOutputType aSVRL = aSCH.applySchematronValidationToSVRL (new FileSystemResource (aXML));
     assertNotNull (aSVRL);
-    if (false)
+    if (true)
       LOGGER.info (new SVRLMarshaller ().getAsString (aSVRL));
 
-    assertEquals (3, SVRLHelper.getAllFailedAssertionsAndSuccessfulReports (aSVRL).size ());
+    assertEquals (12, SVRLHelper.getAllFailedAssertionsAndSuccessfulReports (aSVRL).size ());
   }
 
   @Test
diff --git a/ph-schematron-pure/src/test/resources/external/issues/github170/schematron.sch b/ph-schematron-pure/src/test/resources/external/issues/github170/schematron.sch
index 5bfcc5e95..ffe13ad89 100644
--- a/ph-schematron-pure/src/test/resources/external/issues/github170/schematron.sch
+++ b/ph-schematron-pure/src/test/resources/external/issues/github170/schematron.sch
@@ -1,12 +1,22 @@
 <schema xmlns="http://purl.oclc.org/dsdl/schematron" queryBinding="xpath2">
   <pattern>
-    <rule context="/xml">
-      <let name="stringVar" value="'foo'"/>
-      <assert role="ERROR" test="$stringVar eq 'bar'">error message</assert>
-    </rule>
     <rule context="/xml/owner">
-    <let name="booleanVar" value="1 eq 1"/>
-      <assert role="ERROR" test="$booleanVar eq true()">error message</assert>
+      <let name="stringVar" value="'foo'"/>
+      <let name="booleanVar" value="1 eq 1"/>
+      <let name="booleanVar2" value="true()"/>
+      <let name="numVar" value="123"/>
+      <let name="doubleVar" value="12.345"/>
+      <let name="listVar" value="(1,2,3)"/>
+      <let name="nodeVar" value="."/>
+      <let name="nodeSetVar" value="//owner"/>
+      <assert role="ERROR" test="$stringVar = 'bar'">error message</assert>
+      <assert role="ERROR" test="$booleanVar = false()">error message</assert>
+      <assert role="ERROR" test="$booleanVar2 = false()">error message</assert>
+      <assert role="ERROR" test="$numVar = 17">error message</assert>
+      <assert role="ERROR" test="$doubleVar = 3.14">error message</assert>
+      <assert role="ERROR" test="$listVar = (1, 2)">error message</assert>
+      <assert role="ERROR" test="$nodeVar = ..">error message</assert>
+      <assert role="ERROR" test="$nodeSetVar = ../owner">error message</assert>
     </rule>
   </pattern>
 </schema>