diff --git a/meta-zephyr-core/recipes-kernel/zephyr-kernel/zephyr-toolchain-zephyr.inc b/meta-zephyr-core/recipes-kernel/zephyr-kernel/zephyr-toolchain-zephyr.inc
index e265883..8fa3e09 100644
--- a/meta-zephyr-core/recipes-kernel/zephyr-kernel/zephyr-toolchain-zephyr.inc
+++ b/meta-zephyr-core/recipes-kernel/zephyr-kernel/zephyr-toolchain-zephyr.inc
@@ -18,5 +18,18 @@ EXTRA_OECMAKE:append = " -DUSER_CACHE_DIR=${ZEPHYR_USER_CACHE_DIR}"
 INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
 INHIBIT_PACKAGE_STRIP = "1"
 
+# INHIBIT_DEFAULT_DEPS means no Yocto cross toolchain is built for this recipe,
+# so the exported CC/LD/AR/... point at binaries which do not exist. Zephyr
+# itself ignores them and uses the SDK, but external module build systems
+# invoked by Zephyr (for example Trusted Firmware-A, which is built with its own
+# Makefile) honour them and fail instead of using the SDK passed through
+# CROSS_COMPILE. Keep them out of the task environment.
+ZEPHYR_UNEXPORT_TOOLS = "AR AS CC CPP CXX LD NM OBJCOPY OBJDUMP RANLIB STRIP"
+
+python () {
+    for tool in d.getVar("ZEPHYR_UNEXPORT_TOOLS").split():
+        d.setVarFlag(tool, "unexport", "1")
+}
+
 # Set Zephyr work directory to describe toolchain accurately
 MULTIMACH_TARGET_SYS = "${ZEPHYR_BOARD}-zephyr"