diff --git a/src/json.c b/src/json.c
index db25b70..d0a087a 100644
--- a/src/json.c
+++ b/src/json.c
@@ -607,7 +607,7 @@
     cur_item = res;
     init_tv(&item);
     if (res != NULL)
-    	init_tv(res);
+	init_tv(res);
 
     fill_numbuflen(reader);
     p = reader->js_buf + reader->js_used;
@@ -920,6 +920,15 @@
 	    if (top_item != NULL && top_item->jd_type == JSON_OBJECT_KEY
 		    && cur_item != NULL)
 	    {
+#ifdef FEAT_FLOAT
+		if (cur_item->v_type == VAR_FLOAT)
+		{
+		    // cannot use a float as a key
+		    emsg(_(e_float_as_string));
+		    retval = FAIL;
+		    goto theend;
+		}
+#endif
 		top_item->jd_key = tv_get_string_buf_chk(cur_item, key_buf);
 		if (top_item->jd_key == NULL)
 		{