diff --git a/cmake/QtAutoDetect.cmake b/cmake/QtAutoDetect.cmake
index ba25377abeb..128a882b8dd 100644
--- a/cmake/QtAutoDetect.cmake
+++ b/cmake/QtAutoDetect.cmake
@@ -43,11 +43,7 @@ function(qt_auto_detect_wasm)
                 message(STATUS
                     "Emscripten ${EMCC_VERSION} toolchain file detected at ${CMAKE_TOOLCHAIN_FILE}")
             else()
-                message(FATAL_ERROR
-                    "Cannot find the toolchain file Emscripten.cmake. "
-                    "Please specify the toolchain file with -DCMAKE_TOOLCHAIN_FILE=<file> "
-                    "or provide a path to a valid emscripten installation via the EMSDK "
-                    "environment variable.")
+                __qt_internal_show_error_no_emscripten_toolchain_file_found_when_building_qt()
             endif()
 
             qt_internal_ensure_static_qt_config()
diff --git a/cmake/QtPublicWasmToolchainHelpers.cmake b/cmake/QtPublicWasmToolchainHelpers.cmake
index 53d74e0234c..8d0d9efdc95 100644
--- a/cmake/QtPublicWasmToolchainHelpers.cmake
+++ b/cmake/QtPublicWasmToolchainHelpers.cmake
@@ -53,3 +53,19 @@ function(__qt_internal_get_emcc_recommended_version out_var)
     set(QT_EMCC_RECOMMENDED_VERSION "2.0.14")
     set(${out_var} "${QT_EMCC_RECOMMENDED_VERSION}" PARENT_SCOPE)
 endfunction()
+
+function(__qt_internal_show_error_no_emscripten_toolchain_file_found_when_building_qt)
+    message(FATAL_ERROR
+        "Cannot find the toolchain file Emscripten.cmake. "
+        "Please specify the toolchain file with -DCMAKE_TOOLCHAIN_FILE=<file> "
+        "or provide a path to a valid emscripten installation via the EMSDK "
+        "environment variable.")
+endfunction()
+
+function(__qt_internal_show_error_no_emscripten_toolchain_file_found_when_using_qt)
+    message(FATAL_ERROR
+        "Cannot find the toolchain file Emscripten.cmake. "
+        "Please specify the toolchain file with -DQT_CHAINLOAD_TOOLCHAIN_FILE=<file> "
+        "or provide a path to a valid emscripten installation via the EMSDK "
+        "environment variable.")
+endfunction()
diff --git a/cmake/QtToolchainHelpers.cmake b/cmake/QtToolchainHelpers.cmake
index ce5d7a3fd8d..b10b571ce37 100644
--- a/cmake/QtToolchainHelpers.cmake
+++ b/cmake/QtToolchainHelpers.cmake
@@ -234,14 +234,25 @@ if(DEFINED ENV{EMSDK} AND NOT \"\$ENV{EMSDK}\" STREQUAL \"\")
         \"\${__qt_toolchain_emroot_path}\" _qt_candidate_emscripten_toolchain_path)
     set(__qt_chainload_toolchain_file \"\${_qt_candidate_emscripten_toolchain_path}\")
 endif()
+")
+        list(APPEND init_post_chainload_toolchain "
+if(NOT __qt_chainload_toolchain_file_included)
+    __qt_internal_show_error_no_emscripten_toolchain_file_found_when_using_qt()
+endif()
 ")
     endif()
 
     string(REPLACE ";" "\n" init_additional_used_variables
         "${init_additional_used_variables}")
     string(REPLACE ";" "\n" init_vcpkg "${init_vcpkg}")
+
     string(REPLACE ";" "\n" init_platform "${init_platform}")
     string(REPLACE "LITERAL_SEMICOLON" ";" init_platform "${init_platform}")
+
+    string(REPLACE ";" "\n" init_post_chainload_toolchain "${init_post_chainload_toolchain}")
+    string(REPLACE "LITERAL_SEMICOLON" ";" init_post_chainload_toolchain
+           "${init_post_chainload_toolchain}")
+
     qt_compute_relative_path_from_cmake_config_dir_to_prefix()
     configure_file(
         "${CMAKE_CURRENT_SOURCE_DIR}/cmake/qt.toolchain.cmake.in"
diff --git a/cmake/qt.toolchain.cmake.in b/cmake/qt.toolchain.cmake.in
index 9a8019a3da4..38a7431620d 100644
--- a/cmake/qt.toolchain.cmake.in
+++ b/cmake/qt.toolchain.cmake.in
@@ -43,10 +43,13 @@ if(__qt_chainload_toolchain_file)
             "'${__qt_chainload_toolchain_file}' does not exist.")
     else()
         include("${__qt_chainload_toolchain_file}")
+        set(__qt_chainload_toolchain_file_included TRUE)
     endif()
     unset(__qt_chainload_toolchain_file)
 endif()
 
+@init_post_chainload_toolchain@
+
 # Compute dynamically the Qt installation prefix from the location of this file. This allows
 # the usage of the toolchain file when the Qt installation is relocated.
 get_filename_component(QT_TOOLCHAIN_RELOCATABLE_INSTALL_PREFIX