diff --git a/R/stan-likelihood.R b/R/stan-likelihood.R
index b01cf99e8..dfab1ea6f 100644
--- a/R/stan-likelihood.R
+++ b/R/stan-likelihood.R
@@ -720,7 +720,7 @@ stan_log_lik_inverse.gaussian <- function(bterms, ...) {
   is_pred_shape <- is_pred_dpar(bterms, "shape")
   reqn <- stan_log_lik_adj(bterms) || is_pred_shape
   p <- stan_log_lik_dpars(bterms, reqn = reqn)
-  sdist("inv_gaussian", p$mu, p$shape, vec = !is_pred_shape)
+  sdist("inv_gaussian", p$mu, p$shape, vec = FALSE)
 }
 
 stan_log_lik_wiener <- function(bterms, ...) {