diff --git a/etiquette/photodb.py b/etiquette/photodb.py
index 8731806..705409c 100644
--- a/etiquette/photodb.py
+++ b/etiquette/photodb.py
@@ -768,24 +768,17 @@ class PDBPhotoMixin:
                 self._cached_frozen_children = frozen_children
 
         if tag_expression:
-            expression_tree = expressionmatch.ExpressionTree.parse(tag_expression)
-            expression_tree.map(self.normalize_tagname)
-            expression_matcher = searchhelpers.tag_expression_matcher_builder(
-                frozen_children,
+            tag_expression_tree = searchhelpers.tag_expression_tree_builder(
+                tag_expression=tag_expression,
+                photodb=self,
+                frozen_children=frozen_children,
                 warning_bag=warning_bag,
             )
-            for node in expression_tree.walk_leaves():
-                if node.token in frozen_children:
-                    continue
-
-                exc = exceptions.NoSuchTag(node.token)
-                if warning_bag is not None:
-                    warning_bag.add(exc.error_message)
-                    node.token = None
-                else:
-                    raise exc
-
-            expression_tree.prune()
+            if tag_expression_tree is None:
+                tag_expression = None
+            else:
+                print(tag_expression_tree)
+                tag_match_function = searchhelpers.tag_expression_matcher_builder(frozen_children)
 
         if filename:
             filename_tree = expressionmatch.ExpressionTree.parse(filename)
@@ -859,9 +852,9 @@ class PDBPhotoMixin:
                     continue
 
                 if tag_expression:
-                    success = expression_tree.evaluate(
+                    success = tag_expression_tree.evaluate(
                         photo_tags,
-                        match_function=expression_matcher,
+                        match_function=tag_match_function,
                     )
                     if not success:
                         #print('Failed tag expression')
diff --git a/etiquette/searchhelpers.py b/etiquette/searchhelpers.py
index eb6b299..2eaed38 100644
--- a/etiquette/searchhelpers.py
+++ b/etiquette/searchhelpers.py
@@ -3,6 +3,8 @@ from . import exceptions
 from . import helpers
 from . import objects
 
+from voussoirkit import expressionmatch
+
 def build_query(orderby, notnulls):
     query = 'SELECT * FROM photos'
 
@@ -330,8 +332,48 @@ def normalize_tag_mmf(tags, photodb, warning_bag=None):
 
     return tagset
 
-def tag_expression_matcher_builder(frozen_children, warning_bag=None):
-    def matcher(photo_tags, tagname):
+def tag_expression_tree_builder(
+        tag_expression,
+        photodb,
+        frozen_children,
+        warning_bag=None
+    ):
+    try:
+        expression_tree = expressionmatch.ExpressionTree.parse(tag_expression)
+    except expressionmatch.NoTokens:
+        return None
+    except Exception as exc:
+        warning_bag.add('Bad expression "%s"' % tag_expression)
+        return None
+
+    for node in expression_tree.walk_leaves():
+        try:
+            node.token = photodb.normalize_tagname(node.token)
+        except (exceptions.TagTooShort, exceptions.TagTooLong) as exc:
+            if warning_bag is not None:
+                warning_bag.add(exc.error_message)
+                node.token = None
+            else:
+                raise
+
+        if node.token is None:
+            continue
+
+        if node.token not in frozen_children:
+            exc = exceptions.NoSuchTag(node.token)
+            if warning_bag is not None:
+                warning_bag.add(exc.error_message)
+                node.token = None
+            else:
+                raise exc
+
+    expression_tree.prune()
+    if expression_tree.token is None:
+        return None
+    return expression_tree
+
+def tag_expression_matcher_builder(frozen_children):
+    def match_function(photo_tags, tagname):
         '''
         Used as the `match_function` for the ExpressionTree evaluation.
 
@@ -346,4 +388,4 @@ def tag_expression_matcher_builder(frozen_children, warning_bag=None):
         options = frozen_children[tagname]
         return any(option in photo_tags for option in options)
 
-    return matcher
+    return match_function