diff --git a/language/duchain/navigation/abstractnavigationcontext.cpp b/language/duchain/navigation/abstractnavigationcontext.cpp
--- a/language/duchain/navigation/abstractnavigationcontext.cpp
+++ b/language/duchain/navigation/abstractnavigationcontext.cpp
@@ -21,6 +21,8 @@
 #include <QTextDocument>
 #include <KLocalizedString>
 
+#include <qtcompat_p.h>
+
 #include "abstractdeclarationnavigationcontext.h"
 #include "abstractnavigationwidget.h"
 #include "usesnavigationcontext.h"
@@ -182,7 +184,7 @@
         browser->showUses(action.decl);
         return NavigationContextPointer(this);
       }
-      // fall-through
+      Q_FALLTHROUGH();
     }
     case NavigationAction::ShowUses:
       return registerChild(new UsesNavigationContext(action.decl.data(), this));
diff --git a/language/duchain/stringhelpers.cpp b/language/duchain/stringhelpers.cpp
--- a/language/duchain/stringhelpers.cpp
+++ b/language/duchain/stringhelpers.cpp
@@ -20,6 +20,8 @@
 #include "safetycounter.h"
 #include "util/debug.h"
 
+#include <qtcompat_p.h>
+
 #include <QString>
 #include <QStringList>
 
@@ -170,6 +172,7 @@
       break;
     case '>':
       if( last == '-' ) break;
+      Q_FALLTHROUGH();
     case ')':
       case ']':
         case '}':
@@ -233,6 +236,7 @@
         case '>':
         if( validEnd != ' ' && validEnd != str[a] )
           continue;
+        Q_FALLTHROUGH();
     case ',':
       return a;
     }
diff --git a/plugins/quickopen/quickopenwidget.cpp b/plugins/quickopen/quickopenwidget.cpp
--- a/plugins/quickopen/quickopenwidget.cpp
+++ b/plugins/quickopen/quickopenwidget.cpp
@@ -30,6 +30,8 @@
 #include <icore.h>
 #include <iuicontroller.h>
 
+#include <qtcompat_p.h>
+
 #include <QDialog>
 #include <QMenuBar>
 #include <QKeyEvent>
@@ -414,6 +416,7 @@
           }
           return false;
         }
+        Q_FALLTHROUGH();
       }
       case Qt::Key_PageUp:
       case Qt::Key_PageDown:
diff --git a/qtcompat_p.h b/qtcompat_p.h
--- a/qtcompat_p.h
+++ b/qtcompat_p.h
@@ -39,3 +39,26 @@
 #endif
 
 #endif
+
+// compat for Q_FALLTHROUGH
+#if QT_VERSION < QT_VERSION_CHECK(5,8,0)
+
+#if defined(__has_cpp_attribute)
+#    if __has_cpp_attribute(fallthrough)
+#        define Q_FALLTHROUGH() [[fallthrough]]
+#    elif __has_cpp_attribute(clang::fallthrough)
+#        define Q_FALLTHROUGH() [[clang::fallthrough]]
+#    elif __has_cpp_attribute(gnu::fallthrough)
+#        define Q_FALLTHROUGH() [[gnu::fallthrough]]
+#    endif
+#endif
+
+#ifndef Q_FALLTHROUGH
+#    if defined(__GNUC__) && !defined(__INTEL_COMPILER) && (((__GNUC__ * 100) + __GNUC_MINOR__) >= 700)
+#        define Q_FALLTHROUGH() __attribute__((fallthrough))
+#    else
+#        define Q_FALLTHROUGH() (void)0
+#    endif
+#endif
+
+#endif