diff --git a/tests/psa-client-server/psasim/src/psa_sim_crypto_server.c b/tests/psa-client-server/psasim/src/psa_sim_crypto_server.c
index da3adb0..30d4b26 100644
--- a/tests/psa-client-server/psasim/src/psa_sim_crypto_server.c
+++ b/tests/psa-client-server/psasim/src/psa_sim_crypto_server.c
@@ -2314,3 +2314,8 @@
 
     return ok ? PSA_SUCCESS : PSA_ERROR_GENERIC_ERROR;
 }
+
+void psa_crypto_close(void)
+{
+    psa_sim_serialize_reset();
+}
diff --git a/tests/psa-client-server/psasim/src/psa_sim_generate.pl b/tests/psa-client-server/psasim/src/psa_sim_generate.pl
index 15f5794..43de1db 100755
--- a/tests/psa-client-server/psasim/src/psa_sim_generate.pl
+++ b/tests/psa-client-server/psasim/src/psa_sim_generate.pl
@@ -244,6 +244,16 @@
 }
 EOF
 
+    # Finally, add psa_crypto_close()
+
+    print $fh <<EOF;
+
+void psa_crypto_close(void)
+{
+    psa_sim_serialize_reset();
+}
+EOF
+
     close($fh);
 }
 
diff --git a/tests/psa-client-server/psasim/src/psa_sim_serialise.c b/tests/psa-client-server/psasim/src/psa_sim_serialise.c
index aaf47db..651e046 100644
--- a/tests/psa-client-server/psasim/src/psa_sim_serialise.c
+++ b/tests/psa-client-server/psasim/src/psa_sim_serialise.c
@@ -713,3 +713,11 @@
 
     return 1;
 }
+
+void psa_sim_serialize_reset(void)
+{
+    memset(hash_operation_handles, 0, sizeof(hash_operation_handles));
+    memset(hash_operations, 0, sizeof(hash_operations));
+    memset(aead_operation_handles, 0, sizeof(aead_operation_handles));
+    memset(aead_operations, 0, sizeof(aead_operations));
+}
diff --git a/tests/psa-client-server/psasim/src/psa_sim_serialise.h b/tests/psa-client-server/psasim/src/psa_sim_serialise.h
index 9c69e65..537730c 100644
--- a/tests/psa-client-server/psasim/src/psa_sim_serialise.h
+++ b/tests/psa-client-server/psasim/src/psa_sim_serialise.h
@@ -54,6 +54,12 @@
  * don't contain pointers.
  */
 
+/** Reset all operation slots.
+ *
+ * Should be called when all clients have disconnected.
+ */
+void psa_sim_serialize_reset(void);
+
 /** Return how much buffer space is needed by \c psasim_serialise_begin().
  *
  * \return                   The number of bytes needed in the buffer for
diff --git a/tests/psa-client-server/psasim/src/psa_sim_serialise.pl b/tests/psa-client-server/psasim/src/psa_sim_serialise.pl
index c795fd4..e89fafe 100755
--- a/tests/psa-client-server/psasim/src/psa_sim_serialise.pl
+++ b/tests/psa-client-server/psasim/src/psa_sim_serialise.pl
@@ -105,6 +105,7 @@
         }
     }
 
+    print define_server_serialize_reset(@types);
 } else {
     die("internal error - shouldn't happen");
 }
@@ -329,6 +330,12 @@
  * don't contain pointers.
  */
 
+/** Reset all operation slots.
+ *
+ * Should be called when all clients have disconnected.
+ */
+void psa_sim_serialize_reset(void);
+
 /** Return how much buffer space is needed by \c psasim_serialise_begin().
  *
  * \return                   The number of bytes needed in the buffer for
@@ -913,6 +920,33 @@
 EOF
 }
 
+# Return the code for psa_sim_serialize_reset()
+sub define_server_serialize_reset
+{
+    my @types = @_;
+
+    my $code = <<EOF;
+
+void psa_sim_serialize_reset(void)
+{
+EOF
+
+    for my $type (@types) {
+        next unless $type =~ /^psa_(\w+_operation)_t$/;
+
+        my $what = $1;  # e.g. "hash_operation"
+
+        $code .= <<EOF;
+    memset(${what}_handles, 0, sizeof(${what}_handles));
+    memset(${what}s, 0, sizeof(${what}s));
+EOF
+    }
+
+    $code .= <<EOF;
+}
+EOF
+}
+
 # Horrible way to align first, second and third lines of function signature to
 # appease uncrustify (these are the 2nd-4th lines of code, indices 1, 2 and 3)
 #
diff --git a/tests/psa-client-server/psasim/src/server.c b/tests/psa-client-server/psasim/src/server.c
index 77ce269..10ab5a2 100644
--- a/tests/psa-client-server/psasim/src/server.c
+++ b/tests/psa-client-server/psasim/src/server.c
@@ -54,6 +54,7 @@
     int client_disconnected = 0;
     char mbedtls_version[18];
     extern psa_status_t psa_crypto_call(psa_msg_t msg);
+    extern psa_status_t psa_crypto_close(void);
 
     mbedtls_version_get_string_full(mbedtls_version);
     SERVER_PRINT("%s", mbedtls_version);
@@ -81,6 +82,7 @@
                         SERVER_PRINT("Got a disconnection message");
                         ret = PSA_SUCCESS;
                         client_disconnected = 1;
+                        psa_crypto_close();
                         break;
                     default:
                         SERVER_PRINT("Got an IPC call of type %d", msg.type);