diff --git a/src/libs/3rdparty/cplusplus/CoreTypes.cpp b/src/libs/3rdparty/cplusplus/CoreTypes.cpp
index 0561f660584..4519eabc036 100644
--- a/src/libs/3rdparty/cplusplus/CoreTypes.cpp
+++ b/src/libs/3rdparty/cplusplus/CoreTypes.cpp
@@ -21,10 +21,11 @@
 #include "CoreTypes.h"
 #include "TypeVisitor.h"
 #include "Matcher.h"
-#include "Names.h"
 #include <algorithm>
 
-using namespace CPlusPlus;
+namespace CPlusPlus {
+
+UndefinedType UndefinedType::instance;
 
 void UndefinedType::accept0(TypeVisitor *visitor)
 { visitor->visit(this); }
@@ -204,3 +205,5 @@ bool NamedType::match0(const Type *otherType, Matcher *matcher) const
 
     return false;
 }
+
+} // CPlusPlus
diff --git a/src/libs/3rdparty/cplusplus/CoreTypes.h b/src/libs/3rdparty/cplusplus/CoreTypes.h
index 0db1dd81837..5f2c30e89c6 100644
--- a/src/libs/3rdparty/cplusplus/CoreTypes.h
+++ b/src/libs/3rdparty/cplusplus/CoreTypes.h
@@ -29,11 +29,7 @@ namespace CPlusPlus {
 class CPLUSPLUS_EXPORT UndefinedType : public Type
 {
 public:
-    static UndefinedType *instance()
-    {
-        static UndefinedType t;
-        return &t;
-    }
+    static UndefinedType instance;
 
     const UndefinedType *asUndefinedType() const override
     { return this; }
diff --git a/src/libs/3rdparty/cplusplus/FullySpecifiedType.cpp b/src/libs/3rdparty/cplusplus/FullySpecifiedType.cpp
index 7333f306296..27be623821b 100644
--- a/src/libs/3rdparty/cplusplus/FullySpecifiedType.cpp
+++ b/src/libs/3rdparty/cplusplus/FullySpecifiedType.cpp
@@ -26,15 +26,19 @@
 
 using namespace CPlusPlus;
 
+FullySpecifiedType::FullySpecifiedType() :
+    _type(&UndefinedType::instance), _flags(0)
+{}
+
 FullySpecifiedType::FullySpecifiedType(Type *type) :
     _type(type), _flags(0)
 {
     if (! type)
-        _type = UndefinedType::instance();
+        _type = &UndefinedType::instance;
 }
 
 bool FullySpecifiedType::isValid() const
-{ return _type != UndefinedType::instance(); }
+{ return _type != &UndefinedType::instance; }
 
 
 FullySpecifiedType FullySpecifiedType::qualifiedType() const
@@ -170,7 +174,7 @@ Type &FullySpecifiedType::operator*()
 { return *_type; }
 
 FullySpecifiedType::operator bool() const
-{ return _type != UndefinedType::instance(); }
+{ return _type != &UndefinedType::instance; }
 
 const Type &FullySpecifiedType::operator*() const
 { return *_type; }
diff --git a/src/libs/3rdparty/cplusplus/FullySpecifiedType.h b/src/libs/3rdparty/cplusplus/FullySpecifiedType.h
index ec54b8bdd98..03f82b788ea 100644
--- a/src/libs/3rdparty/cplusplus/FullySpecifiedType.h
+++ b/src/libs/3rdparty/cplusplus/FullySpecifiedType.h
@@ -28,7 +28,8 @@ namespace CPlusPlus {
 class CPLUSPLUS_EXPORT FullySpecifiedType final
 {
 public:
-    FullySpecifiedType(Type *type = nullptr);
+    FullySpecifiedType();
+    FullySpecifiedType(Type *type);
     ~FullySpecifiedType() = default;
 
     bool isValid() const;
diff --git a/src/libs/3rdparty/cplusplus/Type.cpp b/src/libs/3rdparty/cplusplus/Type.cpp
index e9b0f2d3c17..00e84b0a61c 100644
--- a/src/libs/3rdparty/cplusplus/Type.cpp
+++ b/src/libs/3rdparty/cplusplus/Type.cpp
@@ -33,7 +33,7 @@ Type::~Type()
 { }
 
 bool Type::isUndefinedType() const
-{ return this == UndefinedType::instance(); }
+{ return this == &UndefinedType::instance; }
 
 bool Type::isVoidType() const
 { return asVoidType() != nullptr; }