diff --git a/app/patches/apply_grantlee_fix.sh b/app/patches/apply_grantlee_fix.sh
index 05cd16101..98d65af6a 100755
--- a/app/patches/apply_grantlee_fix.sh
+++ b/app/patches/apply_grantlee_fix.sh
@@ -21,10 +21,34 @@ fi
 # Replace the unconditional target_compile_definitions block with a commented
 # explanation to avoid duplicate -D flags.
 
-awk '
-BEGIN{inblock=0}
-/target_compile_definitions\(plainmarkupbuildertest_exec PRIVATE QT_TESTCASE_BUILDDIR/ {inblock=1; print "# QT_TESTCASE_BUILDDIR was previously defined here which could conflict with the"; print "# the definition injected by Qt\'s test configuration. Defining the macro in"; print "# multiple places leads to compiler redefinition errors. The test framework"; print "# already provides this define when needed, so omit the explicit definition"; print "# to avoid duplicate -D flags."; next}
-{ if (inblock) { if (/^endif\(\)/) { inblock=0; next } else next } print }
-' "$TARGET_FILE" > "$TARGET_FILE.tmp" && mv "$TARGET_FILE.tmp" "$TARGET_FILE"
+# export TARGET_FILE for the python subprocess
+TARGET_FILE="$TARGET_FILE"
+export TARGET_FILE
+
+python3 - <<'PY'
+import io,sys
+import os
+TARGET_FILE = os.environ.get('TARGET_FILE')
+if not TARGET_FILE:
+    print('TARGET_FILE not set', file=sys.stderr)
+    sys.exit(2)
+with open(TARGET_FILE, 'r', encoding='utf-8') as f:
+    s = f.read()
+old = 'target_compile_definitions(plainmarkupbuildertest_exec PRIVATE QT_TESTCASE_BUILDDIR'
+if old in s:
+    # remove the line and any surrounding if/endif that only wrap it
+    import re
+    # replace the specific line plus optional surrounding if/endif block with a comment
+    s2 = re.sub(r"if \(NOT GRANTLEE_BUILD_WITH_QT6\)\s*target_compile_definitions\(plainmarkupbuildertest_exec PRIVATE QT_TESTCASE_BUILDDIR[\s\S]*?endif\(\)\n?", \
+                '# QT_TESTCASE_BUILDDIR was previously defined here which could conflict with the\n# the definition injected by Qt\'s test configuration. Defining the macro in\n# multiple places leads to compiler redefinition errors. The test framework\n# already provides this define when needed, so omit the explicit definition\n# to avoid duplicate -D flags.\n', s)
+    if s2==s:
+        # fallback: remove only the line
+        s2 = s.replace('target_compile_definitions(plainmarkupbuildertest_exec PRIVATE QT_TESTCASE_BUILDDIR="${CMAKE_BINARY_DIR}")\n','')
+    s = s2
+with open(TARGET_FILE, 'w', encoding='utf-8') as f:
+    f.write(s)
+print('Applied grantlee fix to', TARGET_FILE)
+PY
+
+
 
-echo "Applied grantlee fix to $TARGET_FILE"
diff --git a/cmake/FindRTI.cmake b/cmake/FindRTI.cmake
index 4c978d0ce..c792256af 100755
--- a/cmake/FindRTI.cmake
+++ b/cmake/FindRTI.cmake
@@ -86,7 +86,10 @@ IF(NOT RTI_DIR)
         if(_found_arch STREQUAL "")
           # fallback: pick any x64Linux* directory under lib
           file(GLOB _rti_arch_dirs RELATIVE "${_RTI_DIR}/lib" "${_RTI_DIR}/lib/x64Linux*")
-          list(GET _rti_arch_dirs 0 _found_arch)
+          list(LENGTH _rti_arch_dirs _rti_arch_dirs_len)
+          if(_rti_arch_dirs_len GREATER 0)
+            list(GET _rti_arch_dirs 0 _found_arch)
+          endif()
         endif()
         if(NOT _found_arch STREQUAL "")
           SET(_rti_gcc_arch "${_found_arch}")