diff --git a/src/corelib/Qt6CTestMacros.cmake b/src/corelib/Qt6CTestMacros.cmake
index ccfa4c5c993..2e0ea919ad7 100644
--- a/src/corelib/Qt6CTestMacros.cmake
+++ b/src/corelib/Qt6CTestMacros.cmake
@@ -32,7 +32,8 @@ if (CMAKE_BUILD_TYPE)
 endif()
 
 if (CMAKE_TOOLCHAIN_FILE)
-  list(APPEND BUILD_OPTIONS_LIST "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}")
+  file(TO_CMAKE_PATH "${CMAKE_TOOLCHAIN_FILE}" _CMAKE_TOOLCHAIN_FILE)
+  list(APPEND BUILD_OPTIONS_LIST "-DCMAKE_TOOLCHAIN_FILE=${_CMAKE_TOOLCHAIN_FILE}")
 endif()
 
 if (CMAKE_VERBOSE_MAKEFILE)