diff --git a/src/core/table.c b/src/core/table.c
index 18191a7a..c7235f64 100644
--- a/src/core/table.c
+++ b/src/core/table.c
@@ -301,6 +301,7 @@ JANET_CORE_FN(cfun_table_new,
               "can be avoided. Returns the new table.") {
     janet_fixarity(argc, 1);
     int32_t cap = janet_getinteger(argv, 0);
+    if (cap < 0) janet_panic("expected positive integer");
     return janet_wrap_table(janet_table(cap));
 }