diff --git a/secure_fw/spm/spm_api.h b/secure_fw/spm/spm_api.h
index 99d35a2..75b921c 100644
--- a/secure_fw/spm/spm_api.h
+++ b/secure_fw/spm/spm_api.h
@@ -106,6 +106,7 @@
                                          * Service signal mask passed by
                                          * psa_wait()
                                          */
+    uint32_t index;                     /* Partition index */
 };
 
 #ifdef TFM_PSA_API