diff --git a/CMakeLists.txt b/CMakeLists.txt
index 698c56a46a1..969549eed28 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -840,6 +840,7 @@ if(NOT MSVC)
   # These flags are not available in GCC-4.8.5. Set only when using clang.
   # Compared against https://gcc.gnu.org/onlinedocs/gcc-4.8.5/gcc/Option-Summary.html
   if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
+    string(APPEND CMAKE_CXX_FLAGS " -Wconstant-conversion")
     string(APPEND CMAKE_CXX_FLAGS " -Wno-invalid-partial-specialization")
     string(APPEND CMAKE_CXX_FLAGS " -Wno-typedef-redefinition")
     string(APPEND CMAKE_CXX_FLAGS " -Wno-unknown-warning-option")