diff --git a/.gitattributes b/.gitattributes
index b97712247..edb36a86a 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,3 +1,5 @@
 .version export-subst
 .gitattributes export-ignore
 .gitignore export-ignore
+appveyor.yml export-ignore
+.travis.yml export-ignore
diff --git a/schemas/ComponentTypeSet.xsd b/schemas/ComponentTypeSet.xsd
index ec58ebac1..c3d3ec3b8 100644
--- a/schemas/ComponentTypeSet.xsd
+++ b/schemas/ComponentTypeSet.xsd
@@ -3,10 +3,8 @@
     <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="W3cXmlAttributes.xsd"/>
     <xs:include schemaLocation="Parameter.xsd"/>
     <xs:complexType name="ComponentType">
-        <xs:sequence>
-            <xs:sequence maxOccurs="unbounded">
-                <xs:group ref="ParameterBlockGroup"/>
-            </xs:sequence>
+        <xs:sequence minOccurs="0" maxOccurs="unbounded">
+            <xs:group ref="ParameterBlockGroup"/>
         </xs:sequence>
         <xs:attributeGroup ref="Nameable"/>
         <xs:attribute name="Extends" use="optional"/>
diff --git a/utility/posix/DynamicLibrary.cpp b/utility/posix/DynamicLibrary.cpp
index 10b5e1706..fc12b7d15 100644
--- a/utility/posix/DynamicLibrary.cpp
+++ b/utility/posix/DynamicLibrary.cpp
@@ -44,7 +44,8 @@ DynamicLibrary::DynamicLibrary(const std::string &path) : _path(osSanitizePathNa
     if (_handle == nullptr) {
 
         const char *dlError = dlerror();
-        throw std::runtime_error((dlError != nullptr) ? dlError : "unknown dlopen error");
+        static const char *unknowDlopenError = "unknown dlopen error";
+        throw std::runtime_error((dlError != nullptr) ? dlError : unknowDlopenError);
     }
 }
 
@@ -60,7 +61,8 @@ void *DynamicLibrary::osGetSymbol(const std::string &symbol) const
     if (sym == nullptr) {
 
         const char *dlError = dlerror();
-        throw std::runtime_error((dlError != nullptr) ? dlError : "unknown dlsym error");
+        static const char *unknowDlsymError = "unknown dlsym error";
+        throw std::runtime_error((dlError != nullptr) ? dlError : unknowDlsymError);
     }
 
     return sym;