diff --git a/src/libcalamares/kdsingleapplicationguard/kdsingleapplicationguard.h b/src/libcalamares/kdsingleapplicationguard/kdsingleapplicationguard.h
index 3bd1e644d..d529fdb3e 100644
--- a/src/libcalamares/kdsingleapplicationguard/kdsingleapplicationguard.h
+++ b/src/libcalamares/kdsingleapplicationguard/kdsingleapplicationguard.h
@@ -34,7 +34,7 @@ public:
     explicit KDSingleApplicationGuard( QObject * parent=nullptr );
     explicit KDSingleApplicationGuard( Policy policy, QObject * parent=nullptr );
     explicit KDSingleApplicationGuard( const QStringList & arguments, QObject * parent=nullptr );
-    explicit KDSingleApplicationGuard( const QStringList & arguments, Policy policy, QObject * parent=0 );
+    explicit KDSingleApplicationGuard( const QStringList & arguments, Policy policy, QObject * parent=nullptr );
     ~KDSingleApplicationGuard();
 
     bool isOperational() const;
diff --git a/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.cpp b/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.cpp
index 23f19051c..f530cc85b 100644
--- a/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.cpp
+++ b/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.cpp
@@ -27,7 +27,7 @@ static Version kdParseQtVersion( const char * const version ) {
     return result;
 }
 
-bool _kdCheckQtVersion_impl( int major, int minor, int patchlevel ) {
+bool _kdCheckQtVersion_impl( unsigned int major, unsigned int minor, unsigned int patchlevel ) {
     static const Version actual = kdParseQtVersion( qVersion() ); // do this only once each run...
     const Version requested = { { static_cast< unsigned char >( major ),
                                   static_cast< unsigned char >( minor ),
diff --git a/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.h b/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.h
index e23b78965..c0e37ac76 100644
--- a/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.h
+++ b/src/libcalamares/kdsingleapplicationguard/kdtoolsglobal.h
@@ -78,7 +78,7 @@ inline T & __kdtools__dereference_for_methodcall( T * o ) {
 
 #define KDAB_SET_OBJECT_NAME( x ) __kdtools__dereference_for_methodcall( x ).setObjectName( QLatin1String( #x ) )
 
-KDTOOLSCORE_EXPORT bool _kdCheckQtVersion_impl( int major, int minor=0, int patchlevel=0 );
+KDTOOLSCORE_EXPORT bool _kdCheckQtVersion_impl( unsigned int major, unsigned int minor=0, unsigned int patchlevel=0 );
 static inline bool kdCheckQtVersion( unsigned int major, unsigned int minor=0, unsigned int patchlevel=0 ) {
     return (major<<16|minor<<8|patchlevel) <= static_cast<unsigned int>(QT_VERSION)
 	|| _kdCheckQtVersion_impl( major, minor, patchlevel );
diff --git a/src/libcalamares/kdsingleapplicationguard/pimpl_ptr.h b/src/libcalamares/kdsingleapplicationguard/pimpl_ptr.h
index 6f01cd64c..b66bd11a2 100644
--- a/src/libcalamares/kdsingleapplicationguard/pimpl_ptr.h
+++ b/src/libcalamares/kdsingleapplicationguard/pimpl_ptr.h
@@ -1,5 +1,5 @@
-#ifndef KDTOOLSCORE__PIMPL_PTR_H
-#define KDTOOLSCORE__PIMPL_PTR_H
+#ifndef KDTOOLSCORE_PIMPL_PTR_H
+#define KDTOOLSCORE_PIMPL_PTR_H
 
 #include "kdtoolsglobal.h"
 
@@ -40,5 +40,5 @@ namespace kdtools {
 } // namespace kdtools
 #endif
 
-#endif /* KDTOOLSCORE__PIMPL_PTR_H */
+#endif /* KDTOOLSCORE_PIMPL_PTR_H */