diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3043c6ab..baa4e582 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -532,7 +532,8 @@ if (TCL_READLINE)
 endif()
 
 # common to gcc/clang
-set(CXX_FLAGS -Wall -Wextra -pedantic -Wcast-qual -Wredundant-decls -Wformat-security)
+set(CXX_FLAGS -Wall -Wextra -pedantic -Wcast-qual -Wredundant-decls
+  -Wformat-security -Werror=misleading-indentation)
 
 if(ENABLE_TSAN)
   message(STATUS "Thread sanitizer: ${ENABLE_TSAN}")