diff --git a/DESCRIPTION b/DESCRIPTION
index 39d6716..424bfd9 100755
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: githist
 Title: Code analyses traced along the 'git' history of a package
-Version: 0.1.0.030
+Version: 0.1.0.031
 Authors@R: 
     person("Mark", "Padgham", , "mark.padgham@email.com", role = c("aut", "cre"),
            comment = c(ORCID = "0000-0003-2172-5265"))
diff --git a/codemeta.json b/codemeta.json
index 69b0d75..6ecfdc1 100644
--- a/codemeta.json
+++ b/codemeta.json
@@ -8,7 +8,7 @@
   "codeRepository": "https://github.com/ropensci-review-tools/githist",
   "issueTracker": "https://github.com/ropensci-review-tools/githist/issues",
   "license": "https://spdx.org/licenses/GPL-3.0",
-  "version": "0.1.0.030",
+  "version": "0.1.0.031",
   "programmingLanguage": {
     "@type": "ComputerLanguage",
     "name": "R",
diff --git a/tests/testthat/test-dashboard.R b/tests/testthat/test-dashboard.R
index 42ffa79..c6f0cc0 100644
--- a/tests/testthat/test-dashboard.R
+++ b/tests/testthat/test-dashboard.R
@@ -2,7 +2,7 @@ pkg <- system.file ("extdata", "testpkg.zip", package = "githist")
 flist <- unzip (pkg, exdir = fs::path_temp ())
 path <- fs::path_dir (flist [1])
 
-res0 <- githist (path)
+res0 <- githist (path, num_cores = 1L)
 
 test_that ("dashboard input errors", {
 
diff --git a/tests/testthat/test-testpkg.R b/tests/testthat/test-testpkg.R
index 0f9e79a..21a2cbf 100644
--- a/tests/testthat/test-testpkg.R
+++ b/tests/testthat/test-testpkg.R
@@ -6,10 +6,11 @@ test_that ("testpkg and input errors", {
     flist <- unzip (pkg, exdir = fs::path_temp ())
     path <- fs::path_dir (flist [1])
 
-    expect_error (githist (path, step_size = 1:2))
-    expect_error (githist (path, step_size = "1"))
+    expect_error (githist (path, step_size = 1:2, num_cores = 1L))
+    expect_error (githist (path, step_size = "1", num_cores = 1L))
 
-    res <- githist (path)
+    res <- githist (path, num_cores = 1L)
+    fs::dir_delete (path)
 
     expect_type (res, "list")
     expect_length (res, 3L)
@@ -22,17 +23,17 @@ test_that ("githist parameters", {
     flist <- unzip (pkg, exdir = fs::path_temp ())
     path <- fs::path_dir (flist [1])
 
-    res0 <- githist (path)
+    res0 <- githist (path, num_cores = 1L)
     n0 <- vapply (res0, nrow, integer (1L))
     fs::dir_delete (path)
 
     flist <- unzip (pkg, exdir = fs::path_temp ())
-    res1 <- githist (path, n = 2L)
+    res1 <- githist (path, n = 2L, num_cores = 1L)
     n1 <- vapply (res1, nrow, integer (1L))
     fs::dir_delete (path)
 
     flist <- unzip (pkg, exdir = fs::path_temp ())
-    res2 <- githist (path, n = 2L, step_size = 2L)
+    res2 <- githist (path, n = 2L, step_size = 2L, num_cores = 1L)
     n2 <- vapply (res2, nrow, integer (1L))
     fs::dir_delete (path)