diff --git a/R/symengine.R b/R/symengine.R
index de69e48d1..16de6f88b 100644
--- a/R/symengine.R
+++ b/R/symengine.R
@@ -2247,7 +2247,7 @@ rxS <- function(x, doConst = TRUE, promoteLinSens = FALSE, envir=parent.frame())
   .env$rx_hi_ <- symengine::S("1")
   if (!is.null(rxode2parse::.rxSEeqUsr())) {
     sapply(names(rxode2parse::.rxSEeqUsr()), function(x) {
-      assign(.rxFunction(x), x, envir = .env)
+      assign(x, .rxFunction(x), envir = .env)
     })
   }
   ## EulerGamma=0.57721566490153286060651209008240243104215933593992
diff --git a/tests/testthat/test-udf.R b/tests/testthat/test-udf.R
index 32dabdd7e..09e32f817 100644
--- a/tests/testthat/test-udf.R
+++ b/tests/testthat/test-udf.R
@@ -295,11 +295,19 @@ rxTest({
   test_that("symengine load", {
 
     mod <- "tke=THETA[1];\nprop.sd=THETA[2];\neta.ke=ETA[1];\nke=gg(tke,exp(eta.ke));\nipre=gg(10,exp(-ke*t));\nlipre=log(ipre);\nrx_yj_~2;\nrx_lambda_~1;\nrx_low_~0;\nrx_hi_~1;\nrx_pred_f_~ipre;\nrx_pred_~rx_pred_f_;\nrx_r_~(rx_pred_f_*prop.sd)^2;\n"
+
     gg <- function(x, y) {
-      PreciseSums::psProd(c(x, y))
+      x * y
     }
 
-    rxS(mod, TRUE, TRUE)
+    expect_error(rxS(mod, TRUE, TRUE), NA)
+
+    rxFun(gg)
+
+    rm(gg)
+
+    expect_error(rxS(mod, TRUE, TRUE), NA)
+
 
   })
 })