diff --git a/cmake/toolchain/zephyr/target.cmake b/cmake/toolchain/zephyr/target.cmake
index 1c3b93bb68879d..b68a8cce18c8b6 100644
--- a/cmake/toolchain/zephyr/target.cmake
+++ b/cmake/toolchain/zephyr/target.cmake
@@ -1,3 +1,34 @@
 # SPDX-License-Identifier: Apache-2.0
 
 include(${ZEPHYR_BASE}/cmake/toolchain/zephyr/${SDK_VERSION}/target.cmake)
+
+
+# For toolchains without a deterministic 'ar' option, see
+# less ideal but tested "strip-nondeterminism" alternative at
+#  https://github.com/marc-hb/zephyr/commits/strip-nondeterminism
+
+# TODO: build future versions of the Zephyr SDK with
+#      --enable-deterministic-archives?
+
+# Ideally we'd want to _append_ -D to the list of flags and operations
+# that cmake already uses by default. However as of version 3.14 cmake
+# doesn't support addition, one can only replace the complete AR command.
+
+# To see what the default flags are and find where they're defined
+# in cmake's code:
+# - comment out the end of the foreach line like this:
+#      foreach(lang ) # ASM C CXX
+# - build any sample with:
+#       2>cmake.log  cmake --trace-expand ...
+# - Search cmake.log for:
+#      CMAKE_.*_ARCHIVE and CMAKE_.*CREATE_STATIC
+
+# CMake's documentation is at node: CMAKE_LANG_CREATE_STATIC_LIBRARY
+
+# At least one .a file needs 'ASM': arch/xtensa/core/startup/ because
+# there's no C file there.
+foreach(lang ASM C CXX)
+  # GNU ar always updates the index: no need for CMAKE_RANLIB
+  SET(CMAKE_${lang}_CREATE_STATIC_LIBRARY
+      "<CMAKE_AR> qcD <TARGET> <LINK_FLAGS> <OBJECTS>")
+endforeach()