diff --git a/mjit.c b/mjit.c
index fb4b153cc3..49bac227a0 100644
--- a/mjit.c
+++ b/mjit.c
@@ -422,8 +422,9 @@ exec_process(const char *path, char *const argv[])
                      : waitpid(pid, &stat, 0);
         if (r == -1) {
             if (errno == EINTR) continue;
-            fprintf(stderr, "[%d] waitpid(%d): %s\n",
-                    getpid(), pid, strerror(errno));
+            fprintf(stderr, "[%d] waitpid(%d): %s (SIGCHLD=%d,%u)\n",
+                    getpid(), pid, strerror(errno),
+                    RUBY_SIGCHLD, SIGCHLD_LOSSY);
             break;
         }
         else if (r == pid) {
diff --git a/vm_core.h b/vm_core.h
index 9db99fe03b..cf2dde01b1 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -101,7 +101,7 @@
 #endif
 
 /* platforms with broken or non-existent SIGCHLD work by polling */
-#if defined(__APPLE__) || defined(__WIN32__)
+#if defined(__APPLE__) || defined(__WIN32__) || defined(_WIN32)
 #  define SIGCHLD_LOSSY (1)
 #else
 #  define SIGCHLD_LOSSY (0)