diff --git a/ChangeLog.d/zeroize_key_buffers_before_free.txt b/ChangeLog.d/zeroize_key_buffers_before_free.txt
new file mode 100644
index 000000000..ba5bae191
--- /dev/null
+++ b/ChangeLog.d/zeroize_key_buffers_before_free.txt
@@ -0,0 +1,4 @@
+Security
+   * Zeroize dynamically-allocated buffers used by the PSA Crypto key storage
+     module before freeing them. These buffers contain secret key material, and
+     could thus potentially leak the key through freed heap.
diff --git a/library/psa_crypto_storage.c b/library/psa_crypto_storage.c
index c6660b955..db7786d6c 100644
--- a/library/psa_crypto_storage.c
+++ b/library/psa_crypto_storage.c
@@ -349,6 +349,7 @@ psa_status_t psa_save_persistent_key( const psa_core_key_attributes_t *attr,
     status = psa_crypto_storage_store( attr->id,
                                        storage_data, storage_data_length );
 
+    mbedtls_platform_zeroize( storage_data, storage_data_length );
     mbedtls_free( storage_data );
 
     return( status );
@@ -394,6 +395,7 @@ psa_status_t psa_load_persistent_key( psa_core_key_attributes_t *attr,
         status = PSA_ERROR_STORAGE_FAILURE;
 
 exit:
+    mbedtls_platform_zeroize( loaded_data, storage_data_length );
     mbedtls_free( loaded_data );
     return( status );
 }