diff --git a/toscaparser/elements/tosca_type_validation.py b/toscaparser/elements/tosca_type_validation.py
index 82b0b46f..5f1409b3 100644
--- a/toscaparser/elements/tosca_type_validation.py
+++ b/toscaparser/elements/tosca_type_validation.py
@@ -48,12 +48,12 @@ class TypeValidation(object):
         for name in custom_type:
             if name not in self.ALLOWED_TYPE_SECTIONS:
                 ExceptionCollector.appendException(
-                    UnknownFieldError(what='Template ' + (self.import_def),
+                    UnknownFieldError(what='Template ' + str(self.import_def),
                                       field=name))
 
     def _validate_type_version(self, version):
         if version not in self.VALID_TEMPLATE_VERSIONS:
             ExceptionCollector.appendException(
                 InvalidTemplateVersion(
-                    what=version + ' in ' + self.import_def,
+                    what=version + ' in ' + str(self.import_def),
                     valid_versions=', '. join(self.VALID_TEMPLATE_VERSIONS)))
diff --git a/toscaparser/tests/data/custom_types/invalid_template_version.yaml b/toscaparser/tests/data/custom_types/invalid_template_version.yaml
new file mode 100644
index 00000000..f5fb7f14
--- /dev/null
+++ b/toscaparser/tests/data/custom_types/invalid_template_version.yaml
@@ -0,0 +1,7 @@
+tosca_definitions_version: tosca_simple_yaml_XXX
+
+node_types:
+
+  tosca.nodes.SomeNode:
+    derived_from: tosca.nodes.SoftwareComponent
+
diff --git a/toscaparser/tests/data/test_import_invalid_template_version.yaml b/toscaparser/tests/data/test_import_invalid_template_version.yaml
new file mode 100644
index 00000000..2ea4647d
--- /dev/null
+++ b/toscaparser/tests/data/test_import_invalid_template_version.yaml
@@ -0,0 +1,13 @@
+tosca_definitions_version: tosca_simple_yaml_1_0
+
+imports:
+  - invalid: custom_types/invalid_template_version.yaml
+
+description: >
+    Test to import a template with an invalid template version.
+
+topology_template:
+  node_templates:
+    test:
+      type: tosca.nodes.SomeNode
+
diff --git a/toscaparser/tests/test_toscatplvalidation.py b/toscaparser/tests/test_toscatplvalidation.py
index 2048a83b..28919daa 100644
--- a/toscaparser/tests/test_toscatplvalidation.py
+++ b/toscaparser/tests/test_toscatplvalidation.py
@@ -1441,6 +1441,18 @@ heat-translator/master/translator/tests/data/custom_types/wordpress.yaml
             (_('The template version "tosca_xyz" is invalid. Valid versions '
                'are "%s".') % valid_versions))
 
+    def test_import_invalid_template_version(self):
+        tosca_tpl = os.path.join(
+            os.path.dirname(os.path.abspath(__file__)),
+            "data/test_import_invalid_template_version.yaml")
+        self.assertRaises(exception.ValidationError, ToscaTemplate, tosca_tpl)
+        valid_versions = ', '.join(ToscaTemplate.VALID_TEMPLATE_VERSIONS)
+        exception.ExceptionCollector.assertExceptionMessage(
+            exception.InvalidTemplateVersion,
+            (_('The template version "tosca_simple_yaml_XXX in '
+               '{\'invalid\': \'custom_types/invalid_template_version.yaml\'}"'
+               ' is invalid. Valid versions are "%s".') % valid_versions))
+
     def test_node_template_capabilities_properties(self):
         # validating capability property values
         tpl_snippet = '''