diff --git a/.gitignore b/.gitignore
index 32ff9af..3216808 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@
 /pyMapVBVD-0.5.4-test-data.tar.xz
 /pyMapVBVD-0.5.5.tar.gz
 /pyMapVBVD-0.5.5-test-data.tar.xz
+/pyMapVBVD-test-data.tar.xz
diff --git a/get_test_data.sh b/get_test_data.sh
index ab40fbd..a43c1ee 100755
--- a/get_test_data.sh
+++ b/get_test_data.sh
@@ -11,8 +11,13 @@ Usage: $1 VERSION
 
 Generate a source archive containing the test data files for pyMapVBVD that are
 tracked in git LFS and are not included in the default source archive. The
-result will be named pyMapVBVD-\${VERSION}-test-data.tar.xz and will be written
+result will be named pyMapVBVD-test-data.tar.xz and will be written
 into the current working directory.
+
+The script attempts to produce a reproducible archive to avoid uploading
+near-duplicate archives to the lookaside cache when the test data does not
+change from one version to the next. Accordingly, the top-level directory
+pyMapVBVD-\${VERSION}/ is omitted from the archived paths.
 EOF
 }
 
@@ -41,7 +46,7 @@ GITDIR="$(echo "${FORGEURL}" | sed -r 's@.*/@@')"
 #SOURCE0="${FORGEURL}/archive/${VERSION}/pdfminer.six-${VERSION}.tar.gz"
 #TARNAME="$(basename "${SOURCE0}")"
 TARDIR="pyMapVBVD-${VERSION}"
-NEWTAR="${TARDIR}-test-data.tar.xz"
+NEWTAR='pyMapVBVD-test-data.tar.xz'
 
 SAVEDIR="${PWD}"
 XDIR="$(mktemp -d)"
@@ -61,8 +66,20 @@ git lfs ls-files -n |
 		ln "${fn}" "${DESTDIR}/$(basename "${fn}")"
 	done
 
-cd "${XDIR}"
-tar -cv "${TARDIR}/" | xz -9e > "${NEWTAR}"
+cd "${XDIR}/${TARDIR}"
+# https://www.gnu.org/software/tar/manual/html_section/Reproducibility.html
+# We discard mtimes entirely, since git doesn’t store mtimes and they are just
+# the time we did the git clone.
+TZ=UTC LC_ALL=C tar \
+		--create --verbose \
+		--sort=name \
+		--format=posix \
+		--numeric-owner --owner=0 --group=0 \
+		--mode=go+u,go-w \
+		--pax-option='delete=atime,delete=ctime' \
+		--clamp-mtime --mtime='@0' \
+		. |
+	xz -9e > "${XDIR}/${NEWTAR}"
 
 cd "${SAVEDIR}"
 mv -v "${XDIR}/${NEWTAR}" .
diff --git a/python-pymapvbvd.spec b/python-pymapvbvd.spec
index d458367..6343b06 100644
--- a/python-pymapvbvd.spec
+++ b/python-pymapvbvd.spec
@@ -11,7 +11,7 @@ License:        MIT AND Unlicense
 URL:            https://github.com/wtclarke/pymapvbvd
 Source0:        %{pypi_source pyMapVBVD}
 # Generated with Source2: ./get_test_data.sh %%{version}
-Source1:        pyMapVBVD-%{version}-test-data.tar.xz
+Source1:        pyMapVBVD-test-data.tar.xz
 Source2:        get_test_data.sh
 
 BuildArch:      noarch
@@ -43,7 +43,7 @@ Summary:        %{summary}
 
 %prep
 %autosetup -n pyMapVBVD-%{version} -p1
-%setup -q -T -D -b 1 -n pyMapVBVD-%{version}
+%setup -q -T -D -a 1 -c -n pyMapVBVD-%{version}
 # We can use the system versioneer to generate _version.py, and can remove the
 # bundled, amaglamated versioneer.py to indicate we aren’t using it.
 rm -v versioneer.py
diff --git a/sources b/sources
index 4562551..bc0690d 100644
--- a/sources
+++ b/sources
@@ -1,2 +1,2 @@
 SHA512 (pyMapVBVD-0.5.5.tar.gz) = 7757d9963879efd4e69c6d61ec3e6fcd98153118f891b958351c720705c57cf48ec3dfc459ab0f69fe00b5d9bddc53621340f7b1f6bb88385408932b9fd32b19
-SHA512 (pyMapVBVD-0.5.5-test-data.tar.xz) = 8b0d548e1100b15942158e240e795b05a82a3c62ae44f4ccaea84977d4373c19d9ae6b93cd42f49823c4fbf113c3470e72431889d6aff870c4c6fed7202befa8
+SHA512 (pyMapVBVD-test-data.tar.xz) = 9fa0530f68b02a8ff26fad1c463db217260c2f31a039b96f30a1fa6bb8b044ab8304edfd06abcaf5e9980ed355f29f0339c6e87e8dbddd67ae85457f384d45dd