diff --git a/options/m_option.h b/options/m_option.h
index f179c75494..bcdc1f9fcc 100644
--- a/options/m_option.h
+++ b/options/m_option.h
@@ -213,6 +213,7 @@ struct m_sub_options {
 };
 
 #define CONF_TYPE_BOOL          (&m_option_type_bool)
+#define CONF_TYPE_FLAG          (&m_option_type_flag)
 #define CONF_TYPE_INT           (&m_option_type_int)
 #define CONF_TYPE_INT64         (&m_option_type_int64)
 #define CONF_TYPE_FLOAT         (&m_option_type_float)
@@ -232,6 +233,7 @@ struct m_sub_options {
 // size/alignment requirements for option values in general.
 union m_option_value {
     bool bool_;
+    int flag; // not the C type "bool"!
     int int_;
     int64_t int64;
     float float_;
diff --git a/player/client.c b/player/client.c
index cf2483b4c2..9b4c83b861 100644
--- a/player/client.c
+++ b/player/client.c
@@ -970,7 +970,7 @@ void mpv_wakeup(mpv_handle *ctx)
 // map client API types to internal types
 static const struct m_option type_conv[] = {
     [MPV_FORMAT_STRING]     = { .type = CONF_TYPE_STRING },
-    [MPV_FORMAT_FLAG]       = { .type = CONF_TYPE_BOOL },
+    [MPV_FORMAT_FLAG]       = { .type = CONF_TYPE_FLAG },
     [MPV_FORMAT_INT64]      = { .type = CONF_TYPE_INT64 },
     [MPV_FORMAT_DOUBLE]     = { .type = CONF_TYPE_DOUBLE },
     [MPV_FORMAT_NODE]       = { .type = CONF_TYPE_NODE },