diff --git a/CMakeLists.txt b/CMakeLists.txt
index a7fcb9b399..b911ccfec2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -213,14 +213,18 @@ if(COMPILE_LUA AND NOT WIN32)
     foreach(CURRENT_LUAC_PRG luac5.1 luac)
       find_program(_CHECK_LUAC_PRG ${CURRENT_LUAC_PRG})
       if(_CHECK_LUAC_PRG)
-        set(LUAC_PRG "${_CHECK_LUAC_PRG} -s -o - %s" CACHE STRING "Format for compiling to Lua bytecode")
+        # Escape "%" for string.format() (in gen_char_blob.lua). #39271
+        string(REPLACE "%" "%%" _LUAC_PRG_ESCAPED "${_CHECK_LUAC_PRG}")
+        set(LUAC_PRG "${_LUAC_PRG_ESCAPED} -s -o - %q" CACHE STRING "Format for compiling to Lua bytecode")
         break()
       endif()
     endforeach()
   elseif(LUA_PRG MATCHES "luajit")
     check_lua_module(${LUA_PRG} "jit.bcsave" LUAJIT_HAS_JIT_BCSAVE)
     if(LUAJIT_HAS_JIT_BCSAVE)
-      set(LUAC_PRG "${LUA_PRG} -b -s %s -" CACHE STRING "Format for compiling to Lua bytecode")
+      # Escape "%" for string.format() (in gen_char_blob.lua). #39271
+      string(REPLACE "%" "%%" _LUA_PRG_ESCAPED "${LUA_PRG}")
+      set(LUAC_PRG "${_LUA_PRG_ESCAPED} -b -s %q -" CACHE STRING "Format for compiling to Lua bytecode")
     endif()
   endif()
 endif()