diff --git a/CMakeLists.txt b/CMakeLists.txt
index 067b30cf3a..4a9c428d4a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -235,6 +235,7 @@ LYX_OPTION(EXTERNAL_BOOST       "Use external boost" ${DefaultExternalLibs} GCC)
 LYX_OPTION(PROGRAM_SUFFIX       "Append version suffix to binaries" ON GCC)
 LYX_OPTION(DEBUG_GLIBC          "Enable libstdc++ debug mode" OFF GCC)
 LYX_OPTION(DEBUG_GLIBC_PEDANTIC "Enable libstdc++ pedantic debug mode" OFF GCC)
+LYX_OPTION(DEBUG_GLIBC_ASSERTIONS "Enable stdlib-assertions debug mode" OFF GCC)
 LYX_OPTION(STDLIB_DEBUG         "Use debug stdlib" ${DefaultLyxStdlibDebug} GCC)
 
 # MSVC specific
@@ -659,6 +660,26 @@ else()
 	set(LYX_DEBUG ON)
 endif()
 
+set(min_qt5_version "5.6")
+if(LYX_USE_QT MATCHES "AUTO")
+	# try qt6 first
+	find_package(Qt6Core CONFIG QUIET)
+	if (Qt6Core_Found)
+		set(LYX_USE_QT "QT6" CACHE STRING "Valid qt version" FORCE)
+		message(STATUS "Qt5Core_VERSION = ${Qt5Core_VERSION}")
+	else()
+		find_package(Qt5Core CONFIG QUIET)
+		if(Qt5Core_FOUND)
+			set(LYX_USE_QT "QT5" CACHE STRING "Valid qt version" FORCE)
+			message(STATUS "Qt5Core_VERSION = ${Qt5Core_VERSION}")
+			if(Qt5Core_VERSION VERSION_LESS ${min_qt5_version})
+				message(FATAL_ERROR "No appropriate QT-version found")
+			endif()
+		else()
+			message(FATAL_ERROR "No appropriate QT-version found")
+		endif()
+	endif()
+endif()
 
 # When shared libs are supported enable this option
 #LYX_OPTION(SHARED_LIBRARIES "Build shared libraries" OFF ALL)
@@ -720,15 +741,20 @@ else()
 	else()
 		set(LYX_CXX_FLAGS "-Wall -Wextra ${LYX_GCC11_MODE}${LYX_CXX_FLAGS}")
 	endif()
-	if(LYX_STDLIB_DEBUG)
-	  set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC")
-        else()
-          if(LYX_DEBUG_GLIBC)
-            set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG")
-          endif()
-          if(LYX_DEBUG_GLIBC_PEDANTIC)
-            set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG_PEDANTIC")
-          endif()
+	message(STATUS "LYX_USE_QT = ${LYX_USE_QT}")
+	if(LYX_USE_QT MATCHES "QT6")
+	  if (LYX_DEBUG_GLIBC OR LYX_DEBUG_GLIBC_PEDANTIC)
+	    message(WARNING "Compiling LyX with stdlib-debug and Qt6 library may lead to crashes. Consider dropping -DLYX_DEBUG_GLIBC=ON and -DLYX_DEBUG_GLIBC_PEDANTIC=ON")
+	  endif()
+	endif()
+	if(LYX_STDLIB_DEBUG OR LYX_DEBUG_GLIBC_ASSERTIONS)
+	  set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_ASSERTIONS")
+	endif()
+	if(LYX_DEBUG_GLIBC)
+	  set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG")
+	endif()
+	if(LYX_DEBUG_GLIBC_PEDANTIC)
+	  set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG_PEDANTIC")
 	endif()
 	set(CMAKE_CXX_FLAGS       "${LYX_CXX_FLAGS} -fno-strict-aliasing " CACHE STRING "Set CXX flags" FORCE)
 	set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g3 -D_DEBUG" CACHE STRING "Set debug flags" FORCE)
@@ -751,27 +777,6 @@ if(LYX_XMINGW)
 	list(APPEND CMAKE_FIND_ROOT_PATH ${GNUWIN32_DIR})
 endif()
 
-set(min_qt5_version "5.6")
-if(LYX_USE_QT MATCHES "AUTO")
-	# try qt6 first
-	find_package(Qt6Core CONFIG QUIET)
-	if (Qt6Core_Found)
-		set(LYX_USE_QT "QT6" CACHE STRING "Valid qt version" FORCE)
-		message(STATUS "Qt5Core_VERSION = ${Qt5Core_VERSION}")
-	else()
-		find_package(Qt5Core CONFIG QUIET)
-		if(Qt5Core_FOUND)
-			set(LYX_USE_QT "QT5" CACHE STRING "Valid qt version" FORCE)
-			message(STATUS "Qt5Core_VERSION = ${Qt5Core_VERSION}")
-			if(Qt5Core_VERSION VERSION_LESS ${min_qt5_version})
-				message(FATAL_ERROR "No appropriate QT-version found")
-			endif()
-		else()
-			message(FATAL_ERROR "No appropriate QT-version found")
-		endif()
-	endif()
-endif()
-
 set(QtCore5CompatLibrary)
 set(QtCore5CompatModule)
 if(LYX_USE_QT MATCHES "QT6|QT5")