diff --git a/ChangeLog b/ChangeLog
index 36b3a51..7d95ee3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2026-07-22  Maximilian Muecke  <muecke.maximilian@gmail.com>
 
+	* R/affine.R (AffineSwaption.default): Correct default handling of the
+	payFixed parameter
 	* src/utils.cpp: Accept "Euribor1W" as an alias for "EuriborSW" in
 	buildIborIndex
 
diff --git a/R/affine.R b/R/affine.R
index b402912..3426f29 100644
--- a/R/affine.R
+++ b/R/affine.R
@@ -52,9 +52,9 @@ AffineSwaption.default <- function(params,
         params$european=TRUE
         warning("affine swaption european flag not set defaulting to european")
     }
-    if(is.null(params$payFix)){
-        params$payFix=TRUE
-        warning("affine swaption payFix flag not set defaulting to pay fix swap")
+    if(is.null(params$payFixed)){
+        params$payFixed=TRUE
+        warning("affine swaption payFixed flag not set defaulting to pay fixed swap")
     }
 
     matYears=as.numeric(params$maturity-params$tradeDate)/365