diff --git a/qemu-log.c b/qemu-log.c
index 1dd3de41ad..1ec70e7e83 100644
--- a/qemu-log.c
+++ b/qemu-log.c
@@ -120,6 +120,8 @@ const CPULogItem cpu_log_items[] = {
     { CPU_LOG_IOPORT, "ioport",
       "show all i/o ports accesses" },
 #endif
+    { LOG_UNIMP, "unimp",
+      "log unimplemented functionality" },
     { 0, NULL, NULL },
 };
 
diff --git a/qemu-log.h b/qemu-log.h
index d1e0f2d98d..40f8b7b0c8 100644
--- a/qemu-log.h
+++ b/qemu-log.h
@@ -34,6 +34,7 @@ static inline bool qemu_log_enabled(void)
 #define CPU_LOG_IOPORT     (1 << 7)
 #define CPU_LOG_TB_CPU     (1 << 8)
 #define CPU_LOG_RESET      (1 << 9)
+#define LOG_UNIMP          (1 << 10)
 
 /* Returns true if a bit is set in the current loglevel mask
  */