diff --git a/qobject/json-lexer.c b/qobject/json-lexer.c
index 7c31c2c8ff..f1a4b5a430 100644
--- a/qobject/json-lexer.c
+++ b/qobject/json-lexer.c
@@ -93,7 +93,8 @@
  *   (apostrophe) instead of %x22 (quotation mark), and can't contain
  *   unescaped apostrophe, but can contain unescaped quotation mark.
  * - Interpolation, if enabled:
- *   interpolation = %((l|ll|I64)[du]|[ipsf])
+ *   The lexer accepts %[A-Za-z0-9]*, and leaves rejecting invalid
+ *   ones to the parser.
  *
  * Note:
  * - Input must be encoded in modified UTF-8.
@@ -116,11 +117,6 @@ enum json_lexer_state {
     IN_NEG_NONZERO_NUMBER,
     IN_KEYWORD,
     IN_INTERP,
-    IN_INTERP_L,
-    IN_INTERP_LL,
-    IN_INTERP_I,
-    IN_INTERP_I6,
-    IN_INTERP_I64,
     IN_WHITESPACE,
     IN_START,
     IN_START_INTERP,            /* must be IN_START + 1 */
@@ -224,39 +220,11 @@ static const uint8_t json_lexer[][256] =  {
     },
 
     /* interpolation */
-    [IN_INTERP_LL] = {
-        ['d'] = JSON_INTERP,
-        ['u'] = JSON_INTERP,
-    },
-
-    [IN_INTERP_L] = {
-        ['d'] = JSON_INTERP,
-        ['l'] = IN_INTERP_LL,
-        ['u'] = JSON_INTERP,
-    },
-
-    [IN_INTERP_I64] = {
-        ['d'] = JSON_INTERP,
-        ['u'] = JSON_INTERP,
-    },
-
-    [IN_INTERP_I6] = {
-        ['4'] = IN_INTERP_I64,
-    },
-
-    [IN_INTERP_I] = {
-        ['6'] = IN_INTERP_I6,
-    },
-
     [IN_INTERP] = {
-        ['d'] = JSON_INTERP,
-        ['i'] = JSON_INTERP,
-        ['p'] = JSON_INTERP,
-        ['s'] = JSON_INTERP,
-        ['u'] = JSON_INTERP,
-        ['f'] = JSON_INTERP,
-        ['l'] = IN_INTERP_L,
-        ['I'] = IN_INTERP_I,
+        TERMINAL(JSON_INTERP),
+        ['A' ... 'Z'] = IN_INTERP,
+        ['a' ... 'z'] = IN_INTERP,
+        ['0' ... '9'] = IN_INTERP,
     },
 
     /*
diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 2855eaaeca..e61cee9e8a 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -453,6 +453,7 @@ static QObject *parse_interpolation(JSONParserContext *ctxt, va_list *ap)
     } else if (!strcmp(token->str, "%f")) {
         return QOBJECT(qnum_from_double(va_arg(*ap, double)));
     }
+    parse_error(ctxt, token, "invalid interpolation '%s'", token->str);
     return NULL;
 }
 
diff --git a/tests/check-qjson.c b/tests/check-qjson.c
index d6fda0786f..83f8a0e6e3 100644
--- a/tests/check-qjson.c
+++ b/tests/check-qjson.c
@@ -1021,7 +1021,8 @@ static void interpolation_unknown(void)
     }
     g_test_trap_subprocess(NULL, 0, 0);
     g_test_trap_assert_failed();
-    g_test_trap_assert_stderr("*Unexpected error*stray '%x'*");
+    g_test_trap_assert_stderr("*Unexpected error*"
+                              "invalid interpolation '%x'*");
 }
 
 static void interpolation_string(void)