diff --git a/core/m_option.c b/core/m_option.c
index fcf8cc6a67..c19d6ae15b 100644
--- a/core/m_option.c
+++ b/core/m_option.c
@@ -1635,7 +1635,8 @@ static int parse_chmap(const m_option_t *opt, struct bstr name,
         return M_OPT_INVALID;
     }
 
-    *(struct mp_chmap *)dst = res;
+    if (dst)
+        *(struct mp_chmap *)dst = res;
 
     return 1;
 }