diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 77c9382c5e..6c05f6cc70 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -1,5 +1,5 @@
 /*
- * JSON Parser 
+ * JSON Parser
  *
  * Copyright IBM, Corp. 2009
  *
@@ -518,7 +518,9 @@ static QObject *parse_literal(JSONParserContext *ctxt)
         /* fall through to JSON_FLOAT */
     }
     case JSON_FLOAT:
-        /* FIXME dependent on locale */
+        /* FIXME dependent on locale; a pervasive issue in QEMU */
+        /* FIXME our lexer matches RFC 7159 in forbidding Inf or NaN,
+         * but those might be useful extensions beyond JSON */
         return QOBJECT(qfloat_from_double(strtod(token->str, NULL)));
     default:
         abort();
diff --git a/qobject/qjson.c b/qobject/qjson.c
index b8cc4ca964..06dc210cbf 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -238,6 +238,15 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent)
         char buffer[1024];
         int len;
 
+        /* FIXME: snprintf() is locale dependent; but JSON requires
+         * numbers to be formatted as if in the C locale. Dependence
+         * on C locale is a pervasive issue in QEMU. */
+        /* FIXME: This risks printing Inf or NaN, which are not valid
+         * JSON values. */
+        /* FIXME: the default precision of 6 for %f often causes
+         * rounding errors; we should be using DBL_DECIMAL_DIG (17),
+         * and only rounding to a shorter number if the result would
+         * still produce the same floating point value.  */
         len = snprintf(buffer, sizeof(buffer), "%f", qfloat_get_double(val));
         while (len > 0 && buffer[len - 1] == '0') {
             len--;
@@ -248,7 +257,7 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent)
         } else {
             buffer[len] = 0;
         }
-        
+
         qstring_append(str, buffer);
         break;
     }