diff --git a/R/epmc_ftxt.r b/R/epmc_ftxt.r
index 87b8299..e8838d2 100644
--- a/R/epmc_ftxt.r
+++ b/R/epmc_ftxt.r
@@ -1,6 +1,6 @@
-#' Fetch Europe PMC full texts
+#' Fetch Europe PMC full text
 #'
-#' This function loads full texts into R. Full texts are in XML format and are
+#' This function loads one full text into R. Full text is in XML format and is
 #' only provided for the Open Access subset of Europe PMC.
 #'
 #' @param ext_id character, PMCID. 
@@ -15,8 +15,8 @@
 #'   epmc_ftxt("PMC3639880")
 #'   }
 epmc_ftxt <- function(ext_id = NULL) {
-  if (!grepl("^PMC", ext_id))
-    stop("Please provide a PMCID, i.e. ids starting with 'PMC'")
+  if (!grepl("^PMC", ext_id) || length(ext_id) != 1)
+    stop("Please provide one PMCID, i.e. id starting with 'PMC'")
   # call api
   req <-
     httr::RETRY("GET",
diff --git a/tests/testthat/test_epmc_ftxt.r b/tests/testthat/test_epmc_ftxt.r
index de75551..ae3053b 100644
--- a/tests/testthat/test_epmc_ftxt.r
+++ b/tests/testthat/test_epmc_ftxt.r
@@ -5,7 +5,7 @@ test_that("epmc_ftxt returns", {
   a <- epmc_ftxt("PMC3257301")
   b <- epmc_ftxt("PMC3639880")
 
-  #correct class metadata
+  # correct class metadata
   expect_is(a, "xml_document")
   expect_is(b, "xml_document")
 
@@ -13,6 +13,6 @@ test_that("epmc_ftxt returns", {
   expect_error(epmc_ftxt("2PMC3448176"))
   expect_error(epmc_ftxt("PMC3476"))
   expect_error(epmc_ftxt("3476"),
-    "Please provide a PMCID, i.e. ids starting with 'PMC'"
-    )
+    "Please provide one PMCID, i.e. id starting with 'PMC'"
+  )
 })