diff --git a/mjit.c b/mjit.c
index ade1e2e6a9..232424fa5d 100644
--- a/mjit.c
+++ b/mjit.c
@@ -422,8 +422,8 @@ exec_process(const char *path, char *const argv[])
                      : waitpid(pid, &stat, 0);
         if (r == -1) {
             if (errno == EINTR) continue;
-            fprintf(stderr, "[%"PRI_PIDT_PREFIX"d] waitpid(%"PRI_PIDT_PREFIX"d): %s (SIGCHLD=%d,%u)\n",
-                    getpid(), pid, strerror(errno),
+            fprintf(stderr, "[%"PRI_PIDT_PREFIX"d] waitpid(%lu): %s (SIGCHLD=%d,%u)\n",
+                    getpid(), (unsigned long)pid, strerror(errno),
                     RUBY_SIGCHLD, SIGCHLD_LOSSY);
             break;
         }
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index fd852c21b7..20b47a581a 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -760,7 +760,7 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
 #define ssize_t int
 !endif
 #define PRI_LL_PREFIX "I64"
-#define PRI_PIDT_PREFIX "I"
+#define PRI_PIDT_PREFIX PRI_INT_PREFIX
 #define GETGROUPS_T int
 #define RETSIGTYPE void
 #define TYPEOF_TIMEVAL_TV_SEC long