diff --git a/src/ludus/grammar.clj b/src/ludus/grammar.clj
index 13c55ee..099de1e 100644
--- a/src/ludus/grammar.clj
+++ b/src/ludus/grammar.clj
@@ -174,7 +174,7 @@
 
 (defp synthetic group order-1 [synth-root (zero+ synth-term)])
 
-(defp fn-clause group order-1 [tuple-pattern (maybe constraint) (quiet :rarrow) expression])
+(defp fn-clause group order-1 [tuple-pattern (maybe guard) (quiet :rarrow) expression])
 
 (defp fn-entry order-1 [fn-clause terminators])