diff --git a/runtime/caml/domain_state.tbl b/runtime/caml/domain_state.tbl
index 27a625ff6..8093020fa 100644
--- a/runtime/caml/domain_state.tbl
+++ b/runtime/caml/domain_state.tbl
@@ -76,7 +76,7 @@ DOMAIN_STATE(intnat, stat_heap_chunks)
 /* See gc_ctrl.c */
 
 DOMAIN_STATE(uintnat, eventlog_startup_timestamp)
-DOMAIN_STATE(uint32_t, eventlog_startup_pid)
+DOMAIN_STATE(long, eventlog_startup_pid)
 DOMAIN_STATE(uintnat, eventlog_paused)
 DOMAIN_STATE(uintnat, eventlog_enabled)
 DOMAIN_STATE(FILE*, eventlog_out)
diff --git a/runtime/eventlog.c b/runtime/eventlog.c
index 6d3bd7ca7..2ed452da1 100644
--- a/runtime/eventlog.c
+++ b/runtime/eventlog.c
@@ -139,12 +139,12 @@ static void setup_eventlog_file()
   eventlog_filename = caml_secure_getenv(T("OCAML_EVENTLOG_PREFIX"));
 
   if (eventlog_filename) {
-    int ret = snprintf_os(output_file, OUTPUT_FILE_LEN, T("%s.%d.eventlog"),
+    int ret = snprintf_os(output_file, OUTPUT_FILE_LEN, T("%s.%ld.eventlog"),
                          eventlog_filename, Caml_state->eventlog_startup_pid);
     if (ret > OUTPUT_FILE_LEN)
       caml_fatal_error("eventlog: specified OCAML_EVENTLOG_PREFIX is too long");
   } else {
-    snprintf_os(output_file, OUTPUT_FILE_LEN, T("caml-%d.eventlog"),
+    snprintf_os(output_file, OUTPUT_FILE_LEN, T("caml-%ld.eventlog"),
                Caml_state->eventlog_startup_pid);
   }