diff --git a/R/import.spc.R b/R/import.spc.R
index 9537455..f9cc87e 100644
--- a/R/import.spc.R
+++ b/R/import.spc.R
@@ -178,6 +178,10 @@ print.import.spc <- function(x, ...){
 
 ext_ser_call <- function(spc, vname){
   if (is.null(spc)) return(NULL)
+  
+  # the default data format for X-13 is "free"
+  fformat <- ifelse(is.null(spc$format), "free", spc$format)
+  frm <- rem_quotes(fformat)
 
   # analyze series spec
   if ("data" %in% names(spc)){
@@ -190,9 +194,7 @@ ext_ser_call <- function(spc, vname){
                 ", start = ", deparse(start), ", frequency = ", f, ")")
 
   } else if ("file" %in% names(spc)){
-
-    frm <- rem_quotes(spc$format)
-
+    
     # fragment for name, for fortran and x11 series
     if (!is.null(spc$name)) {
       nm <- rem_quotes(spc$name)
diff --git a/tests/testthat/_snaps/ext_ser_call.md b/tests/testthat/_snaps/ext_ser_call.md
new file mode 100644
index 0000000..4ead03e
--- /dev/null
+++ b/tests/testthat/_snaps/ext_ser_call.md
@@ -0,0 +1,14 @@
+# ext_ser_call()
+
+    Code
+      ext_ser_call(pp, "x")
+    Output
+      [1] "x <- import.ts(file.dat)"
+
+# ext_ser_call() defaults to format "free"
+
+    Code
+      ext_ser_call(pp, "x")
+    Output
+      [1] "x <- import.ts(file.dat, format = \"free\", start = c(2014, 1), frequency = 12, name = \"xyz\")"
+
diff --git a/tests/testthat/test-ext_ser_call.R b/tests/testthat/test-ext_ser_call.R
new file mode 100644
index 0000000..9829d65
--- /dev/null
+++ b/tests/testthat/test-ext_ser_call.R
@@ -0,0 +1,32 @@
+test_that("ext_ser_call()", {
+  
+  pp <- list(
+    title = "abc",
+    start = 2014.01,
+    period = 12,
+    save = c("a1", "b1"),
+    print = "brief",
+    format = "datevalue",
+    name = "xyz",
+    file = "file.dat"
+  )
+  
+  expect_snapshot(ext_ser_call(pp, "x"))  
+  
+})
+
+test_that("ext_ser_call() defaults to format \"free\"", {
+  
+  pp <- list(
+    title = "abc",
+    start = 2014.01,
+    period = 12,
+    save = c("a1", "b1"),
+    print = "brief",
+    name = "xyz",
+    file = "file.dat"
+  )
+  
+  expect_snapshot(ext_ser_call(pp, "x"))
+  
+})