diff --git a/cmake/modules/extensions.cmake b/cmake/modules/extensions.cmake
index 35fa6b3a0f8..35711a27b77 100644
--- a/cmake/modules/extensions.cmake
+++ b/cmake/modules/extensions.cmake
@@ -5302,6 +5302,11 @@ function(add_llext_target target_name)
        OUTPUT_VARIABLE llext_remove_flags_regexp
   )
   string(REPLACE ";" "|" llext_remove_flags_regexp "${llext_remove_flags_regexp}")
+  if ("${llext_remove_flags_regexp}" STREQUAL "")
+    # an empty regexp would match anything, we actually need the opposite
+    # so set it to match empty strings
+    set(llext_remove_flags_regexp "^$")
+  endif()
   set(zephyr_flags
       "$<TARGET_PROPERTY:zephyr_interface,INTERFACE_COMPILE_OPTIONS>"
   )