diff --git a/cmake/compiler/arcmwdt/compiler_flags.cmake b/cmake/compiler/arcmwdt/compiler_flags.cmake
index 7de892c7ee6..6b334c1fe84 100644
--- a/cmake/compiler/arcmwdt/compiler_flags.cmake
+++ b/cmake/compiler/arcmwdt/compiler_flags.cmake
@@ -116,7 +116,7 @@ set_compiler_property(PROPERTY warning_error_misra_sane -Werror=vla)
 set_compiler_property(PROPERTY cstd -std=)
 
 if (NOT CONFIG_ARCMWDT_LIBC)
-  set_compiler_property(PROPERTY nostdinc -Hno_default_include -Hnoarcexlib)
+  set_compiler_property(PROPERTY nostdinc -Hno_default_include -Hnoarcexlib -U__STDC_LIB_EXT1__)
   set_compiler_property(APPEND PROPERTY nostdinc_include ${NOSTDINC})
 endif()