diff --git a/test/pdfs/ohkubo-SS04.pdf.link b/test/pdfs/ohkubo-SS04.pdf.link
index 979ad7bc..c771cf3c 100644
--- a/test/pdfs/ohkubo-SS04.pdf.link
+++ b/test/pdfs/ohkubo-SS04.pdf.link
@@ -1 +1 @@
-http://www.sapid.org/html2/PDF-ja/ohkubo-SS04.pdf
\ No newline at end of file
+https://web.archive.org/web/20160113135557/http://www.sapid.org/html2/PDF-ja/ohkubo-SS04.pdf
diff --git a/test/pdfs/pal-o47.pdf.link b/test/pdfs/pal-o47.pdf.link
index e45c4873..3f02cdf9 100644
--- a/test/pdfs/pal-o47.pdf.link
+++ b/test/pdfs/pal-o47.pdf.link
@@ -1 +1 @@
-http://www1.cpdl.org/wiki/images/sheet/pal-o47.pdf
+https://web.archive.org/web/20091007190143/http://www.cpdl.org/wiki/images/sheet/pal-o47.pdf
diff --git a/test/pdfs/pdf.pdf.link b/test/pdfs/pdf.pdf.link
index bbc2b3a1..b8afb995 100644
--- a/test/pdfs/pdf.pdf.link
+++ b/test/pdfs/pdf.pdf.link
@@ -1 +1 @@
-http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_1-7.pdf
\ No newline at end of file
+https://web.archive.org/web/20151204084826/http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_1-7.pdf
diff --git a/test/pdfs/piperine.pdf.link b/test/pdfs/piperine.pdf.link
index 0d38690e..d3967200 100644
--- a/test/pdfs/piperine.pdf.link
+++ b/test/pdfs/piperine.pdf.link
@@ -1 +1 @@
-http://www.erowid.org/archive/rhodium/chemistry/3base/piperonal.pepper/piperine.pepper/465e03piperine.pdf
+https://web.archive.org/web/20151019020657/https://www.erowid.org/archive/rhodium/chemistry/3base/piperonal.pepper/piperine.pepper/465e03piperine.pdf
diff --git a/test/pdfs/preistabelle.pdf.link b/test/pdfs/preistabelle.pdf.link
index f48f8565..7be89d95 100644
--- a/test/pdfs/preistabelle.pdf.link
+++ b/test/pdfs/preistabelle.pdf.link
@@ -1 +1 @@
-http://www.fyve.de/downloads/Preistabelle_FYVE_Oktober_2010.pdf
+https://web.archive.org/web/20130903113659/http://www.fyve.de/downloads/Preistabelle_FYVE_Oktober_2010.pdf