2 files changed, 7 insertions, 0 deletions
diff --git a/lib.c b/lib.c
index 0fdc8ef0..7f797bb1 100644
--- a/lib.c
+++ b/lib.c
@@ -3575,8 +3575,12 @@ static val tuples_func(val n, val lcons)
 
 val tuples(val n, val seq, val fill)
 {
+  val self = lit("tuples");
   seq = nullify(seq);
 
+  if (!plusp(n) || !integerp(n))
+    uw_throwf(error_s, lit("~a: positive integer required, not ~s"), self, n, nao);
+
   if (!seq)
     return nil;
 
diff --git a/tests/012/seq.tl b/tests/012/seq.tl
index d434ad52..d27adcef 100644
--- a/tests/012/seq.tl
+++ b/tests/012/seq.tl
@@ -212,3 +212,6 @@
   [separate chr-isalpha "a1b2c3d4"] ("abcd" "1234")
   [separate chrp "a1b2c3d4"] ("a1b2c3d4" "")
   [separate integerp "a1b2c3d4"] ("" "a1b2c3d4"))
+
+(mtest
+  (tuples 0 '(1 2 3)) :error)