diff --git a/.docker/docker-qgis-build.sh b/.docker/docker-qgis-build.sh
index ce1a9049c9b..6386f7ea108 100755
--- a/.docker/docker-qgis-build.sh
+++ b/.docker/docker-qgis-build.sh
@@ -112,7 +112,7 @@ cmake \
  -DWITH_SERVER_LANDINGPAGE_WEBAPP=${WITH_QT5} \
  -DWITH_ORACLE=${WITH_QT5} \
  -DWITH_PDAL=ON \
- -DWITH_QT5SERIALPORT=${WITH_QT5} \
+ -DWITH_QT5SERIALPORT=ON \
  -DWITH_QTWEBKIT=${WITH_QT5} \
  -DWITH_OAUTH2_PLUGIN=${WITH_QT5} \
  -DORACLE_INCLUDEDIR=/instantclient_19_9/sdk/include/ \
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9db221cf061..6496039a298 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -455,11 +455,11 @@ if(WITH_CORE)
   endif()
 
   # Use Qt5SerialPort optionally for GPS
-  set (WITH_QT5SERIALPORT TRUE CACHE BOOL "Determines whether Qt5SerialPort should be tried for GPS positioning")
-  if (WITH_QT5SERIALPORT)
+  set (WITH_QTSERIALPORT TRUE CACHE BOOL "Determines whether Qt5SerialPort should be tried for GPS positioning")
+  if (WITH_QTSERIALPORT)
       find_package(${QT_VERSION_BASE} COMPONENTS SerialPort REQUIRED)
       # following variable is used in qgsconfig.h
-      set (HAVE_QT5SERIALPORT TRUE)
+      set (HAVE_QTSERIALPORT TRUE)
   endif()
 
   find_package(${QT_VERSION_BASE} COMPONENTS Core Gui Widgets Network Xml Svg Concurrent Test Sql Positioning REQUIRED)