diff --git a/.Rbuildignore b/.Rbuildignore
index 180367d..210fb0e 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -2,3 +2,5 @@
 ^NEWS\.md$          # A news file written in Markdown
 ^\.travis\.yml$     # Used for continuous integration testing with travis
 ^data-raw$          # Ignore raw data: not needed for the pkg itself
+^doc$
+^Meta$
diff --git a/R/zzz.R b/R/zzz.R
index 77c9d24..0f1a8e5 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -96,7 +96,7 @@ check.tool.function <- function(frontend = FALSE) {
         # need to require a specific version (2.4.1) of viennaRNA for support of the used commands
 	version <- NULL
     	try (version <- system2("RNAfold", "--version", stdout = TRUE, stderr = TRUE))
-        if (length(attr(version, "status")) == 0) {
+        if (!is(version, "try-error")) {
             # the command worked -> check the version string
             v <- strsplit(version, " ")[[1]]
             if (length(v) >= 2) {