diff --git a/CMakeLists.txt b/CMakeLists.txt
index 88d81593578..c9953597a6b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,6 +19,11 @@ endif()
 # don't relink it only the shared object changes
 set(CMAKE_LINK_DEPENDS_NO_SHARED ON)
 
+# This needs to be set before any add_directory in order to be visible
+# by the subdirectories
+set(QGIS_TEST_TMP_DIR "${CMAKE_BINARY_DIR}/tmp")
+message (STATUS "Ctest Temp Directory set to: ${QGIS_TEST_TMP_DIR}")
+
 #############################################################
 # Project and version
 set(CPACK_PACKAGE_VERSION_MAJOR "3")
diff --git a/cmake/UsePythonTest.cmake b/cmake/UsePythonTest.cmake
index 874d22c3a64..18593162ca9 100644
--- a/cmake/UsePythonTest.cmake
+++ b/cmake/UsePythonTest.cmake
@@ -77,6 +77,9 @@ macro(ADD_PYTHON_TEST TESTNAME FILENAME)
     set_tests_properties(${TESTNAME} PROPERTIES TIMEOUT ${TEST_TIMEOUT})
   endif()
 
-  set_tests_properties(${TESTNAME} PROPERTIES FIXTURES_REQUIRED SOURCETREE)
+  set_tests_properties(${TESTNAME} PROPERTIES
+      FIXTURES_REQUIRED SOURCETREE
+      ENVIRONMENT "TMPDIR=${QGIS_TEST_TMP_DIR};QGIS_CUSTOM_CONFIG_PATH=${QGIS_TEST_TMP_DIR}/config"
+  )
 
 endmacro(ADD_PYTHON_TEST)
diff --git a/tests/src/3d/testqgs3drendering.cpp b/tests/src/3d/testqgs3drendering.cpp
index 76caea4fbe3..867bf6c3610 100644
--- a/tests/src/3d/testqgs3drendering.cpp
+++ b/tests/src/3d/testqgs3drendering.cpp
@@ -1752,7 +1752,7 @@ void TestQgs3DRendering::do3DSceneExport( int zoomLevelsCount, int expectedObjec
   exporter.setScale( 1.0 );
 
   QVERIFY( exporter.parseVectorLayerEntity( scene->layerEntity( layerPoly ), layerPoly ) );
-  exporter.save( QString( "test3DSceneExporter-%1" ).arg( zoomLevelsCount ), "/tmp/" );
+  exporter.save( QString( "test3DSceneExporter-%1" ).arg( zoomLevelsCount ), QDir::tempPath() );
 
   int sum = 0;
   for ( auto o : exporter.mObjects )
diff --git a/tests/src/CMakeLists.txt b/tests/src/CMakeLists.txt
index a653575ad4d..92f88aec1eb 100644
--- a/tests/src/CMakeLists.txt
+++ b/tests/src/CMakeLists.txt
@@ -26,7 +26,11 @@ if (ENABLE_TESTS)
       set_tests_properties(${TESTNAME} PROPERTIES LABELS ${ARG_QGIS_TEST_LABELS})
     endif()
 
-    set_tests_properties(${TESTNAME} PROPERTIES FIXTURES_REQUIRED SOURCETREE)
+    set_tests_properties(${TESTNAME} PROPERTIES
+      FIXTURES_REQUIRED SOURCETREE
+      ENVIRONMENT "TMPDIR=${QGIS_TEST_TMP_DIR};QGIS_CUSTOM_CONFIG_PATH=${QGIS_TEST_TMP_DIR}/config"
+    )
+
     target_compile_definitions(${TESTNAME} PRIVATE "CMAKE_SOURCE_DIR=\"${CMAKE_SOURCE_DIR}\"")
   endmacro()
 
diff --git a/tests/src/core/testqgslabelingengine.cpp b/tests/src/core/testqgslabelingengine.cpp
index 37366863826..7d20e93ff22 100644
--- a/tests/src/core/testqgslabelingengine.cpp
+++ b/tests/src/core/testqgslabelingengine.cpp
@@ -4346,7 +4346,7 @@ void TestQgsLabelingEngine::labelingResultsWithCallouts()
   job.start();
   job.waitForFinished();
 
-  job.renderedImage().save( QStringLiteral( "/tmp/renderer.png" ) );
+  job.renderedImage().save( QString( "%s/renderer.png" ).arg( QDir::tempPath() ) );
 
   std::unique_ptr< QgsLabelingResults > results( job.takeLabelingResults() );
   QVERIFY( results );
diff --git a/tests/src/core/testqgsproject.cpp b/tests/src/core/testqgsproject.cpp
index bda528eb36b..7437ced09d3 100644
--- a/tests/src/core/testqgsproject.cpp
+++ b/tests/src/core/testqgsproject.cpp
@@ -1083,6 +1083,7 @@ void TestQgsProject::testAsynchronousLayerLoading()
   int layersCount = layers.count();
 
   project->addMapLayers( layers );
+  project->writeEntry( QStringLiteral( "Paths" ), QStringLiteral( "Absolute" ), true );
 
   QCOMPARE( project->mapLayers( true ).count(), layersCount - 2 );
   QCOMPARE( project->mapLayers( false ).count(), layersCount );