diff --git a/Meta/Lagom/CMakeLists.txt b/Meta/Lagom/CMakeLists.txt
index b4c29c8cf9..6d1b0a8a28 100644
--- a/Meta/Lagom/CMakeLists.txt
+++ b/Meta/Lagom/CMakeLists.txt
@@ -57,6 +57,7 @@ endif()
 
 include(wasm_spec_tests)
 
+add_compile_options(-fsigned-char)
 add_compile_options(-Wno-unknown-warning-option -Wno-literal-suffix -Wno-implicit-const-int-float-conversion)
 add_compile_options(-O2)
 add_compile_options(-Wall -Wextra -Werror)