diff --git a/local/recipes/qt/redox-toolchain.cmake b/local/recipes/qt/redox-toolchain.cmake
index fe74e9610e..cae3527408 100644
--- a/local/recipes/qt/redox-toolchain.cmake
+++ b/local/recipes/qt/redox-toolchain.cmake
@@ -42,13 +42,13 @@ set(CMAKE_SYSTEM_VERSION 1)
 
 # Redox userspace currently must not emit CET/IBT entry instructions (endbr64),
 # because they trap as invalid opcode in the current runtime stack.
-# Ensure C99 stdlib declarations (strtold etc.) are visible before Qt headers
-# pull in <cstdlib>. Needed for KF6/Qt C++ builds on relibc which declares
-# strtold but implements it via libredbear-qt-strtold-compat.so.
 set(CMAKE_C_FLAGS "-fcf-protection=none -march=x86-64 -include strings.h -include stdlib.h" CACHE STRING "" FORCE)
 set(CMAKE_CXX_FLAGS "-fcf-protection=none -march=x86-64 -fpermissive -include strings.h -include stdlib.h -I${COOKBOOK_SYSROOT}/usr/include/QtQml -I${COOKBOOK_SYSROOT}/usr/include/QtQuick" CACHE STRING "" FORCE)
 set(CMAKE_C_FLAGS_RELEASE "-fcf-protection=none -march=x86-64 -include strings.h -include stdlib.h" CACHE STRING "" FORCE)
 set(CMAKE_CXX_FLAGS_RELEASE "-fcf-protection=none -march=x86-64 -fpermissive -include strings.h -include stdlib.h" CACHE STRING "" FORCE)
+# Disable precompiled headers — PCH compiles without -include flags,
+# missing C99 stdlib declarations (strtold) needed by GCC <cstdlib>.
+set(CMAKE_DISABLE_PRECOMPILE_HEADERS ON CACHE BOOL "" FORCE)
 
 # Flag for redox.patch: enables REDOX-specific CMake code paths (mkspec, QPA plugin).
 # QtPlatformSupport.cmake checks this variable. Set as CACHE INTERNAL so it persists