diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -52,7 +52,7 @@
     RunnerSyntax
     QueryMatch
 
-    PREFIX KRunner
+    PREFIX Plasma
     REQUIRED_HEADERS KRunner_HEADERS
 )
 
@@ -63,13 +63,13 @@
         ${KF5_INSTALL_TARGETS_DEFAULT_ARGS})
 
 install(FILES ${KRunner_CamelCase_HEADERS}
-        DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/KRunner
+        DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/Plasma
         COMPONENT Devel)
 
 install(FILES
             ${CMAKE_CURRENT_BINARY_DIR}/krunner_export.h
             ${KRunner_HEADERS}
-        DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/krunner
+        DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/plasma
         COMPONENT Devel)
 
 install(FILES
@@ -107,3 +107,92 @@
    "data/org.kde.krunner1.xml"
    DESTINATION ${KDE_INSTALL_DBUSINTERFACEDIR}
    RENAME kf5_org.kde.krunner1.xml)
+
+
+# Backward compatibility: install also to wrong C++ namespace path layer KRunner/ & krunner/
+# KF6: remove
+
+include(CMakeParseArguments)
+
+# loosely modeled after ECM_GENERATE_HEADERS
+function(GENERATE_BACKWARDHEADERS camelcase_forwarding_headers_var)
+    set(options)
+    set(oneValueArgs PREFIX BACKWARD_PREFIX REQUIRED_HEADERS)
+    set(multiValueArgs HEADER_NAMES)
+    cmake_parse_arguments(GBH "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+    if (GBH_UNPARSED_ARGUMENTS)
+        message(FATAL_ERROR "Unexpected arguments to GENERATE_BACKWARDHEADERS: ${GBH_UNPARSED_ARGUMENTS}")
+    endif()
+
+    if(NOT GBH_HEADER_NAMES OR NOT GBH_PREFIX OR NOT GBH_BACKWARD_PREFIX OR NOT GBH_REQUIRED_HEADERS)
+       message(FATAL_ERROR "Missing argument HEADER_NAMES, PREFIX, BACKWARD_PREFIX or REQUIRED_HEADERS to GENERATE_BACKWARDHEADERS")
+    endif()
+
+    set(GBH_OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+
+    if (NOT "${GBH_PREFIX}" MATCHES "^.*/$")
+        set(GBH_PREFIX "${GBH_PREFIX}/")
+    endif()
+    string(TOLOWER "${GBH_PREFIX}" originalprefix)
+
+    if (NOT "${GBH_BACKWARD_PREFIX}" MATCHES "^.*/$")
+        set(GBH_BACKWARD_PREFIX "${GBH_BACKWARD_PREFIX}/")
+    endif()
+    string(TOLOWER "${GBH_BACKWARD_PREFIX}" originalbackwardprefix)
+
+    foreach(_CLASSNAME ${GBH_HEADER_NAMES})
+        string(TOLOWER "${_CLASSNAME}" originalclassname)
+
+        set(_actualheader "${CMAKE_CURRENT_SOURCE_DIR}/${originalclassname}.h")
+        if (NOT EXISTS ${_actualheader})
+            message(FATAL_ERROR "Could not find \"${_actualheader}\"")
+        endif()
+
+        # CamelCase forwarding header
+        set(FANCY_HEADER_FILE "${GBH_OUTPUT_DIR}/${GBH_BACKWARD_PREFIX}${_CLASSNAME}")
+        if (NOT EXISTS ${FANCY_HEADER_FILE})
+            file(WRITE ${FANCY_HEADER_FILE}
+                "#warning Use of header <${GBH_BACKWARD_PREFIX}${_CLASSNAME}> is deprecated since KRunner v5.44, switch to <${GBH_PREFIX}${_CLASSNAME}>\n"
+                "#include <${originalprefix}${originalclassname}.h>\n"
+            )
+        endif()
+        list(APPEND ${camelcase_forwarding_headers_var} "${FANCY_HEADER_FILE}")
+
+        # normal forwarding header
+        set(REGULAR_HEADER_NAME ${GBH_OUTPUT_DIR}/${originalbackwardprefix}${originalclassname}.h)
+        if (NOT EXISTS ${REGULAR_HEADER_NAME})
+            file(WRITE ${REGULAR_HEADER_NAME}
+                "#warning Use of header <${originalbackwardprefix}${originalclassname}.h> is deprecated since KRunner v5.44, switch to <${originalprefix}${originalclassname}.h>\n"
+                "#include <${originalprefix}${originalclassname}.h>\n"
+            )
+        endif()
+        list(APPEND _REQUIRED_HEADERS "${REGULAR_HEADER_NAME}")
+    endforeach()
+
+    set(${camelcase_forwarding_headers_var} ${${camelcase_forwarding_headers_var}} PARENT_SCOPE)
+    set(${GBH_REQUIRED_HEADERS} ${${GBH_REQUIRED_HEADERS}} ${_REQUIRED_HEADERS} PARENT_SCOPE)
+endfunction()
+
+generate_backwardheaders(KRunner_CamelCase_BACKWARD_HEADERS
+  HEADER_NAMES
+    AbstractRunner
+    RunnerContext
+    RunnerManager
+    RunnerSyntax
+    QueryMatch
+
+    PREFIX Plasma
+    BACKWARD_PREFIX KRunner
+    REQUIRED_HEADERS KRunner_BACKWARD_HEADERS
+)
+
+install(FILES ${KRunner_CamelCase_BACKWARD_HEADERS}
+    DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/KRunner
+    COMPONENT Devel
+)
+install(FILES ${KRunner_BACKWARD_HEADERS}
+        ${CMAKE_CURRENT_BINARY_DIR}/krunner_export.h # also simple copy just in case someone includes it
+    DESTINATION ${KF5_INCLUDE_INSTALL_DIR}/KRunner/krunner
+    COMPONENT Devel
+)
diff --git a/src/abstractrunner.h b/src/abstractrunner.h
--- a/src/abstractrunner.h
+++ b/src/abstractrunner.h
@@ -47,7 +47,7 @@
 class AbstractRunnerPrivate;
 
 /**
- * @class AbstractRunner abstractrunner.h <KRunner/AbstractRunner>
+ * @class AbstractRunner abstractrunner.h <Plasma/AbstractRunner>
  *
  * @short An abstract base class for Plasma Runner plugins.
  *
diff --git a/src/dbusrunner_p.h b/src/dbusrunner_p.h
--- a/src/dbusrunner_p.h
+++ b/src/dbusrunner_p.h
@@ -18,7 +18,7 @@
 
 #pragma once
 
-#include <KRunner/AbstractRunner>
+#include <Plasma/AbstractRunner>
 
 #include "dbusutils_p.h"
 class OrgKdeKrunner1Interface;
diff --git a/src/dbusutils_p.h b/src/dbusutils_p.h
--- a/src/dbusutils_p.h
+++ b/src/dbusutils_p.h
@@ -4,7 +4,7 @@
 #include <QString>
 #include <QDBusArgument>
 #include <QVariantMap>
-#include <KRunner/QueryMatch>
+#include <Plasma/QueryMatch>
 
 struct RemoteMatch
 {
diff --git a/src/declarative/runnermodel.h b/src/declarative/runnermodel.h
--- a/src/declarative/runnermodel.h
+++ b/src/declarative/runnermodel.h
@@ -23,7 +23,7 @@
 #include <QAbstractListModel>
 #include <QStringList>
 
-#include <KRunner/QueryMatch>
+#include <Plasma/QueryMatch>
 
 namespace Plasma
 {
diff --git a/src/declarative/runnermodel.cpp b/src/declarative/runnermodel.cpp
--- a/src/declarative/runnermodel.cpp
+++ b/src/declarative/runnermodel.cpp
@@ -25,7 +25,7 @@
 
 #include "krunner_debug.h"
 
-#include <KRunner/RunnerManager>
+#include <Plasma/RunnerManager>
 
 RunnerModel::RunnerModel(QObject *parent)
     : QAbstractListModel(parent),
diff --git a/src/declarative/runnermodelplugin.cpp b/src/declarative/runnermodelplugin.cpp
--- a/src/declarative/runnermodelplugin.cpp
+++ b/src/declarative/runnermodelplugin.cpp
@@ -23,7 +23,7 @@
 
 #include "krunner_debug.h"
 
-#include <KRunner/QueryMatch>
+#include <Plasma/QueryMatch>
 
 #include "runnermodel.h"
 
diff --git a/src/querymatch.h b/src/querymatch.h
--- a/src/querymatch.h
+++ b/src/querymatch.h
@@ -40,7 +40,7 @@
 class QueryMatchPrivate;
 
 /**
- * @class QueryMatch querymatch.h <KRunner/QueryMatch>
+ * @class QueryMatch querymatch.h <Plasma/QueryMatch>
  *
  * @short A match returned by an AbstractRunner in response to a given
  * RunnerContext.
diff --git a/src/runnercontext.h b/src/runnercontext.h
--- a/src/runnercontext.h
+++ b/src/runnercontext.h
@@ -36,7 +36,7 @@
 class RunnerContextPrivate;
 
 /**
- * @class RunnerContext runnercontext.h <KRunner/RunnerContext>
+ * @class RunnerContext runnercontext.h <Plasma/RunnerContext>
  *
  * @short The RunnerContext class provides information related to a search,
  *        including the search term, metadata on the search term and collected
diff --git a/src/runnermanager.h b/src/runnermanager.h
--- a/src/runnermanager.h
+++ b/src/runnermanager.h
@@ -41,7 +41,7 @@
     class RunnerManagerPrivate;
 
 /**
- * @class RunnerManager runnermanager.h <KRunner/RunnerManager>
+ * @class RunnerManager runnermanager.h <Plasma/RunnerManager>
  *
  * @short The RunnerManager class decides what installed runners are runnable,
  *        and their ratings. It is the main proxy to the runners.
diff --git a/src/runnersyntax.h b/src/runnersyntax.h
--- a/src/runnersyntax.h
+++ b/src/runnersyntax.h
@@ -29,7 +29,7 @@
 
 class RunnerSyntaxPrivate;
 /**
- * @class RunnerSyntax runnersyntax.h <KRunner/RunnerSyntax>
+ * @class RunnerSyntax runnersyntax.h <Plasma/RunnerSyntax>
  * @since 4.3
  *
  * Represents a query prototype that the runner accepts. These can be
diff --git a/templates/runner/CMakeLists.txt b/templates/runner/CMakeLists.txt
--- a/templates/runner/CMakeLists.txt
+++ b/templates/runner/CMakeLists.txt
@@ -3,7 +3,7 @@
 project(%{APPNAMELC})
 
 set(QT_MIN_VERSION "5.9.0")
-set(KF5_MIN_VERSION "5.42.0")
+set(KF5_MIN_VERSION "5.44.0")
 
 find_package(ECM ${KF5_MIN_VERSION} REQUIRED NO_MODULE)
 set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR})
diff --git a/templates/runner/src/%{APPNAMELC}.h b/templates/runner/src/%{APPNAMELC}.h
--- a/templates/runner/src/%{APPNAMELC}.h
+++ b/templates/runner/src/%{APPNAMELC}.h
@@ -18,7 +18,7 @@
 #ifndef %{APPNAMEUC}_H
 #define %{APPNAMEUC}_H
 
-#include <KRunner/AbstractRunner>
+#include <Plasma/AbstractRunner>
 
 class %{APPNAME} : public Plasma::AbstractRunner
 {