diff --git a/src/core/client.c b/src/core/client.c
index 654b4fb..d7016ec 100644
--- a/src/core/client.c
+++ b/src/core/client.c
@@ -160,7 +160,7 @@ struct client_ctx *add_external_client(struct server_ctx *sctx, char *id) {
 
 static void process_client_message_impl(struct server_ctx *sctx, struct client_ctx *ctx, const criterion_protocol_msg *msg) {
     message_handler *handler = message_handlers[msg->data.which_value];
-    bool ack;
+    bool ack = false;
     if (handler)
         ack = handler(sctx, ctx, msg);
 
@@ -176,7 +176,7 @@ static void process_client_message_impl(struct server_ctx *sctx, struct client_c
 
 struct client_ctx *process_client_message(struct server_ctx *ctx, const criterion_protocol_msg *msg) {
     if (msg->version != PROTOCOL_V1) {
-        handler_error(ctx, "%s", "", "Received message using invalid protocol version number '%d'.", msg->version);
+        handler_error(ctx, "%s", "", "Received message using invalid protocol version number '%" PRIi32 "'.", msg->version);
         return NULL;
     }
 
@@ -187,7 +187,7 @@ struct client_ctx *process_client_message(struct server_ctx *ctx, const criterio
             if (k != kh_end(ctx->subprocesses)) {
                 client = &kh_value(ctx->subprocesses, k);
             } else {
-                handler_error(ctx, "%s", "", "Received message identified by a PID '%ld' "
+                handler_error(ctx, "%s", "", "Received message identified by a PID '%" PRIi64 "' "
                         "that is not a child process.", msg->id.pid);
             }
         } break;
diff --git a/src/core/runner.c b/src/core/runner.c
index f56f94e..8141e5b 100644
--- a/src/core/runner.c
+++ b/src/core/runner.c
@@ -179,7 +179,7 @@ void run_test_child(struct criterion_test *test,
     }
 
     // Notify the runner that the test was born
-    criterion_protocol_msg msg = criterion_message(birth);
+    criterion_protocol_msg msg = criterion_message(birth, .has_timestamp = false);
     criterion_message_set_id(msg);
     cr_send_to_runner(&msg);
 
diff --git a/src/core/theories.c b/src/core/theories.c
index f969cc3..0b370c8 100644
--- a/src/core/theories.c
+++ b/src/core/theories.c
@@ -200,7 +200,7 @@ void cr_theory_main(struct criterion_datapoints *dps, size_t datapoints, void (*
     size_t *indices = malloc(sizeof (size_t) * datapoints);
     memset(indices, 0, datapoints * sizeof (size_t));
 
-    int round = 1;
+    volatile int round = 1;
     volatile bool has_next = true;
     while (has_next) {
         char *name = NULL;