diff --git a/src/bsplines.cpp b/src/bsplines.cpp
index b523ebf..dc4b2c1 100644
--- a/src/bsplines.cpp
+++ b/src/bsplines.cpp
@@ -23,7 +23,7 @@ Rcpp::NumericMatrix cpp_bsplines(arma::vec x, arma::vec iknots, arma::vec bknots
 Rcpp::NumericMatrix cpp_bsplinesD1(arma::vec x, arma::vec iknots, arma::vec bknots, unsigned int order) {
 
   if ((order - 1) <= 0) {
-    Rf_error("(order - 1) <= 0");
+    Rcpp::stop("(order - 1) <= 0");
   }
 
   bbasis B0(x, iknots, bknots, order);
@@ -74,7 +74,7 @@ Rcpp::NumericMatrix cpp_bsplinesD1(arma::vec x, arma::vec iknots, arma::vec bkno
 Rcpp::NumericMatrix cpp_bsplinesD2(arma::vec x, arma::vec iknots, arma::vec bknots, unsigned int order) {
 
   if ((order - 2) <= 0) {
-    Rf_error("(order - 2) <= 0");
+    Rcpp::stop("(order - 2) <= 0");
   }
 
   bbasis B0(x, iknots, bknots, order);
diff --git a/src/cpr.cpp b/src/cpr.cpp
index 7f0caa9..c7c13e3 100644
--- a/src/cpr.cpp
+++ b/src/cpr.cpp
@@ -32,7 +32,7 @@ bbasis::bbasis(arma::vec& x_, arma::vec & iknots_, arma::vec & bknots_, unsigned
   }
 
   if (!xi.is_sorted()) {
-    Rf_error("Knots are not sorted.");
+    Rcpp::stop("Knots are not sorted.");
   }
 
   // define xi_star
diff --git a/tests/test-bsplineD.R b/tests/test-bsplineD.R
index 83f84ad..5d1204c 100644
--- a/tests/test-bsplineD.R
+++ b/tests/test-bsplineD.R
@@ -75,15 +75,15 @@ with(e, {
   stopifnot(isTRUE( all.equal(cprD2[-100, ], baseD2[-100, ])))
 
   x <- tryCatch(bsplineD(xvec, derivative = 1.5), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "Only first and second derivatives are supported"))
 
   x <- tryCatch(bsplineD(xvec, derivative = 3), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "Only first and second derivatives are supported"))
 
   x <- tryCatch(bsplineD(xvec, order = 2, derivative = 2), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "(order - 2) <= 0"))
 })
 
@@ -97,16 +97,16 @@ with(e, {
   bmatD1  <- tryCatch(bsplineD(xvec, bknots = bknots, order = 1, derivative = 1L), error = function(e) e)
   bmatD2  <- tryCatch(bsplineD(xvec, bknots = bknots, order = 1, derivative = 2L), error = function(e) e)
 
-  stopifnot(inherits(bmat, "simpleError"))
-  stopifnot(inherits(bmatD1, "simpleError"))
-  stopifnot(inherits(bmatD2, "simpleError"))
+  stopifnot(inherits(bmat, "error"))
+  stopifnot(inherits(bmatD1, "error"))
+  stopifnot(inherits(bmatD2, "error"))
 
   stopifnot(identical(bmat$message, "order needs to be an integer value >= 2."))
   stopifnot(identical(bmatD1$message, "order needs to be an integer value >= 2."))
   stopifnot(identical(bmatD2$message, "order needs to be an integer value >= 2."))
 
   bmat <- tryCatch(bsplines(xvec, bknots = bknots, order = 1.9), error = function(e) e)
-  stopifnot(inherits(bmat, "simpleError"))
+  stopifnot(inherits(bmat, "error"))
   stopifnot(identical(bmat$message, "order needs to be an integer value >= 2."))
 
   bmat <- tryCatch(bsplines(xvec, bknots = bknots, order = 2.9), error = function(e) e)
diff --git a/tests/test-bsplines.R b/tests/test-bsplines.R
index b24a993..bb8f2c1 100644
--- a/tests/test-bsplines.R
+++ b/tests/test-bsplines.R
@@ -68,7 +68,7 @@ with(e, {
   bknots = c(-1, 1)
 
   x <- tryCatch(bsplines(xvec, iknots = iknots, bknots = bknots), error = function(e) {e})
-  stopifnot(inherits(x, "simpleError"))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "Knots are not sorted."))
 
   x <- tryCatch(bsplines(xvec, iknots = sort(iknots), bknots = bknots), error = function(e) {e})
@@ -92,7 +92,7 @@ with(e, {
 e <- new.env()
 with(e, {
   x <- tryCatch(bsplines(list(1:10)), error = function(e) { e })
-  stopifnot(inherits(x, "simpleError"))
+  stopifnot(inherits(x, "error"))
   stopifnot("error if list passed to bsplines" = identical(x$message, "x is a list. Use btensor instead of bsplines."))
 })
 
@@ -104,7 +104,7 @@ with(e, {
   bknots <- c(-1, 1)
 
   x <- tryCatch(bsplines(xvec, df = 2, bknots = bknots), warning = function(w) {w})
-  stopifnot(identical(class(x), c("simpleWarning", "warning", "condition")))
+  stopifnot(inherits(x, "warning"))
   stopifnot(identical(x$message, "df being set to order"))
 
   x <- suppressWarnings(bsplines(xvec, df = 2, bknots = bknots))
@@ -118,7 +118,7 @@ with(e, {
   stopifnot(isTRUE(all.equal(x, z, check.attributes = FALSE)))
 
   x <- tryCatch(bsplines(xvec, iknots = 0.2, df = 6, bknots = bknots), warning = function(w) {w})
-  stopifnot(identical(class(x), c("simpleWarning", "warning", "condition")))
+  stopifnot(inherits(x, "warning"))
   stopifnot(identical(x$message, "Both iknots and df defined, using iknots"))
 
   x <- suppressWarnings(bsplines(xvec, iknots = 0.2, df = 6, bknots = bknots))
@@ -210,16 +210,16 @@ with(e, {
   stopifnot(isTRUE( all.equal(cprD2[-100, ], baseD2[-100, ])))
 
   x <- tryCatch(bsplineD(xvec, derivative = 1.5), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "Only first and second derivatives are supported"))
   rm(x)
 
   x <- tryCatch(bsplineD(xvec, derivative = 3), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "Only first and second derivatives are supported"))
 
   x <- tryCatch(bsplineD(xvec, order = 2, derivative = 2), error = function(e) {e})
-  stopifnot(identical(class(x), c("simpleError", "error", "condition")))
+  stopifnot(inherits(x, "error"))
   stopifnot(identical(x$message, "(order - 2) <= 0"))
 })
 
@@ -233,16 +233,16 @@ with(e, {
   bmatD1  <- tryCatch(bsplineD(xvec, bknots = bknots, order = 1, derivative = 1L), error = function(e) e)
   bmatD2  <- tryCatch(bsplineD(xvec, bknots = bknots, order = 1, derivative = 2L), error = function(e) e)
 
-  stopifnot(inherits(bmat, "simpleError"))
-  stopifnot(inherits(bmatD1, "simpleError"))
-  stopifnot(inherits(bmatD2, "simpleError"))
+  stopifnot(inherits(bmat, "error"))
+  stopifnot(inherits(bmatD1, "error"))
+  stopifnot(inherits(bmatD2, "error"))
 
   stopifnot(identical(bmat$message, "order needs to be an integer value >= 2."))
   stopifnot(identical(bmatD1$message, "order needs to be an integer value >= 2."))
   stopifnot(identical(bmatD2$message, "order needs to be an integer value >= 2."))
 
   bmat <- tryCatch(bsplines(xvec, bknots = bknots, order = 1.9), error = function(e) e)
-  stopifnot(inherits(bmat, "simpleError"))
+  stopifnot(inherits(bmat, "error"))
   stopifnot(identical(bmat$message, "order needs to be an integer value >= 2."))
 
   bmat <- tryCatch(bsplines(xvec, bknots = bknots, order = 2.9), error = function(e) e)
diff --git a/tests/test-order_statistics.R b/tests/test-order_statistics.R
index ecd9c3f..58b4e84 100644
--- a/tests/test-order_statistics.R
+++ b/tests/test-order_statistics.R
@@ -76,11 +76,11 @@ e <- new.env()
 with(e, {
   d <- tryCatch(d_order_statistic(x = x, n = 4:6, j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(d, "simpleError"))
+  stopifnot(inherits(d, "error"))
   stopifnot(d$message == "length(n) == 1 is not TRUE")
   p <- tryCatch(p_order_statistic(q = x, n = 4:6, j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(p, "simpleError"))
+  stopifnot(inherits(p, "error"))
   stopifnot(p$message == "length(n) == 1 is not TRUE")
 })
 rm(e)
@@ -89,12 +89,12 @@ e <- new.env()
 with(e, {
   d <- tryCatch(d_order_statistic(x = x, n = numeric(0), j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(d, "simpleError"))
+  stopifnot(inherits(d, "error"))
   stopifnot(d$message == "length(n) == 1 is not TRUE")
 
   p <- tryCatch(p_order_statistic(q = x, n = numeric(0), j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(p, "simpleError"))
+  stopifnot(inherits(p, "error"))
   stopifnot(p$message == "length(n) == 1 is not TRUE")
 })
 rm(e)
@@ -103,12 +103,12 @@ e <- new.env()
 with(e, {
   d <- tryCatch(d_order_statistic(x = 0, n = NA_real_, j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(d, "simpleError"))
+  stopifnot(inherits(d, "error"))
   stopifnot(d$message == "!is.na(n) is not TRUE")
 
   p <- tryCatch(p_order_statistic(q = 0, n = NA_real_, j = 2, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(p, "simpleError"))
+  stopifnot(inherits(p, "error"))
   stopifnot(p$message == "!is.na(n) is not TRUE")
 })
 rm(e)
@@ -117,12 +117,12 @@ e <- new.env()
 with(e, {
   d <- tryCatch(d_order_statistic(x = 0, n = 10, j = 11, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(d, "simpleError"))
+  stopifnot(inherits(d, "error"))
   stopifnot(d$message == "n >= stats::na.omit(j) is not TRUE")
 
   p <- tryCatch(p_order_statistic(q = 0, n = 10, j = 11, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(p, "simpleError"))
+  stopifnot(inherits(p, "error"))
   stopifnot(p$message == "n >= stats::na.omit(j) is not TRUE")
 })
 rm(e)
@@ -131,12 +131,12 @@ e <- new.env()
 with(e, {
   d <- tryCatch(d_order_statistic(x = 0, n = 10, j = -1, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(d, "simpleError"))
+  stopifnot(inherits(d, "error"))
   stopifnot(d$message == "stats::na.omit(j) >= 1 is not TRUE")
 
   p <- tryCatch(p_order_statistic(q = 0, n = 10, j = -1, distribution = "norm")
                 , error = function(e) e)
-  stopifnot(inherits(p, "simpleError"))
+  stopifnot(inherits(p, "error"))
   stopifnot(p$message == "stats::na.omit(j) >= 1 is not TRUE")
 })
 rm(e)