diff --git a/vitrage/graph/networkx_algorithm.py b/vitrage/graph/networkx_algorithm.py
index c02ec6357..d72c244ab 100644
--- a/vitrage/graph/networkx_algorithm.py
+++ b/vitrage/graph/networkx_algorithm.py
@@ -44,8 +44,8 @@ class NXAlgorithm(GraphAlgorithm):
             match_func = create_predicate(query_dict)
 
         if not match_func(root_data):
-            LOG.info('graph_query_vertices: root ' + str(root_id) +
-                     ' does not match filter ' + str(query_dict) + ')')
+            LOG.info('graph_query_vertices: root %s does not match filter %s',
+                     str(root_id), str(query_dict))
             return None
 
         n_result = []
diff --git a/vitrage/graph/networkx_graph.py b/vitrage/graph/networkx_graph.py
index a2d39cbd6..de2582d16 100644
--- a/vitrage/graph/networkx_graph.py
+++ b/vitrage/graph/networkx_graph.py
@@ -16,9 +16,7 @@ import copy
 import json
 
 import networkx as nx
-
 from networkx.readwrite import json_graph
-
 from oslo_log import log as logging
 
 from driver import Direction
@@ -84,16 +82,15 @@ class NXGraph(Graph):
         properties = self._g.node.get(v_id, None)
         if properties is not None:
             return vertex_copy(v_id, properties)
-        LOG.debug("get_vertex item not found. v_id=" + str(v_id))
+        LOG.debug("get_vertex item not found. v_id=%s", str(v_id))
         return None
 
     def get_edge(self, source_id, target_id, label):
         try:
             properties = self._g.adj[source_id][target_id][label]
         except KeyError:
-            LOG.debug("get_edge item not found. source_id=" + str(source_id) +
-                      ", target_id=" + str(target_id) +
-                      ", label=" + str(label))
+            LOG.debug("get_edge item not found. source_id=%s, target_id=%s, "
+                      "label=%s", str(source_id), str(target_id), str(label))
             return None
         if properties is not None:
             return edge_copy(source_id, target_id, label, properties)
diff --git a/vitrage/graph/query.py b/vitrage/graph/query.py
index 9020deda2..3e0f7a02f 100644
--- a/vitrage/graph/query.py
+++ b/vitrage/graph/query.py
@@ -64,12 +64,14 @@ def create_predicate(query_dict):
     """
     try:
         expression = _create_query_expression(query=query_dict)
-        LOG.debug('create_predicate::', expression)
+        LOG.debug('create_predicate::%s', expression)
         expression = 'lambda item: ' + expression
         return eval(expression)
     except Exception as e:
-        LOG.error('invalid query format', query_dict, e)
-        raise VitrageError('invalid query format', query_dict, e)
+        LOG.error('invalid query format %s. Exception: %s',
+                  query_dict, e)
+        raise VitrageError('invalid query format %s. Exception: %s',
+                           query_dict, e)
 
 
 def _create_query_expression(query, parent_operator=None):
diff --git a/vitrage/graph/sub_graph_matching.py b/vitrage/graph/sub_graph_matching.py
index cf3084959..f1c2d0e77 100644
--- a/vitrage/graph/sub_graph_matching.py
+++ b/vitrage/graph/sub_graph_matching.py
@@ -128,7 +128,8 @@ def sub_graph_matching(_graph_, sub_graph, known_matches):
     initial_sg = create_initial_sub_graph(_graph_, known_matches, sub_graph)
     if not initial_sg:
         LOG.warning('sub_graph_matching: Initial sub-graph creation failed')
-        LOG.warning('sub_graph_matching: Known matches: ' + str(known_matches))
+        LOG.warning('sub_graph_matching: Known matches: %s',
+                    str(known_matches))
         return final_sub_graphs
     _queue_ = [initial_sg]