diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e4f389ac..90e2066c 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -55,7 +55,7 @@ jobs:
       with:
         version: '6.2.4'
     - name: cmake
-      run: mkdir cbuild; cd cbuild; cmake -DCMAKE_C_COMPILER=gcc-12 -DCMAKE_CXX_COMPILER=g++-13 ..
+      run: mkdir cbuild; cd cbuild; cmake ..
     - name: make
       run: cd cbuild; make
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9e56593a..e7feaf20 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -54,12 +54,12 @@ cmake_minimum_required(VERSION 3.14.0)
 
 project(XaoS)
 
-# use gcc also Mac because Apple clang lacks quadmath support
-set(CMAKE_C_COMPILER gcc)
-set(CMAKE_CXX_COMPILER g++)
+# WARNING: by setting gcc-13.2 and g++-13.2 it is possible to use quadmath support on Mac:
+# set(CMAKE_C_COMPILER gcc-13.2)
+# set(CMAKE_CXX_COMPILER g++-13.2)
 
-# add definitions (remove -DUSE_FLOAT128 if you have a slow machine)
-add_definitions(-DUSE_FLOAT128 -DUSE_SFFE -DSFFE_CMPLX_GSL)
+# WARNING: add -DUSE_FLOAT128 if you want to enable deep zoom via quadmath (may be unsupported on Mac)
+add_definitions(-DUSE_SFFE -DSFFE_CMPLX_GSL)
 
 # resolve symbolic links
 set(CMAKE_FIND_PACKAGE_RESOLVE_SYMLINKS TRUE)
@@ -105,7 +105,7 @@ set(MACOSX_BUNDLE_ICON_FILE XaoS.icns)
 set(XaoS_ICON ${CMAKE_CURRENT_SOURCE_DIR}/src/ui/XaoS.icns)
 set_source_files_properties(${XaoS_ICON} PROPERTIES MACOSX_PACKAGE_LOCATION "Resources")
 
-# Multilingual support: *.ts -> build/*.qm
+# Multilingual support: *.ts -> *.qm
 FIND_PACKAGE(Qt6LinguistTools)
 file(GLOB TRANSLATION_FILES ${CMAKE_CURRENT_SOURCE_DIR}/i18n/*.ts)
 
@@ -130,7 +130,8 @@ add_executable(XaoS MACOSX_BUNDLE
 target_link_libraries(XaoS
    Qt6::Widgets
    Qt6::PrintSupport
-   quadmath
+# WARNING: uncomment the next line if you want to enable deep zoom:
+   # quadmath
 )
 
 # install bundle