diff --git a/docker/build_scripts/py36-requirements.txt b/docker/build_scripts/py36-requirements.txt
index 269ccfe4..6269c84c 100644
--- a/docker/build_scripts/py36-requirements.txt
+++ b/docker/build_scripts/py36-requirements.txt
@@ -1,8 +1,8 @@
 # pip requirements for cpython 3.6
 # NOTE: certifi has GPG signatures; could download and verify independently.
-certifi==2018.1.18 \
-    --hash=sha256:14131608ad2fd56836d33a71ee60fa1c82bc9d2c8d98b7bdbc631fe1b3cd1296 \
-    --hash=sha256:edbc3f203427eef571f79a7692bb160a2b0f7ccaa31953e99bd17e307cf63f7d
+certifi==2018.4.16 \
+    --hash=sha256:9fa520c1bacfb634fa7af20a76bcbd3d5fb390481724c597da32c719a7dca4b0 \
+    --hash=sha256:13e698f54293db9f89122b0581843a782ad0934a4fe0172d2a980ba77fc61bb7
 auditwheel==1.8.0 \
     --hash=sha256:63468bf62d82b27b1635ffe1c3f1c4e54ef67d0a6d38bedccc38ce6965d56db7 \
     --hash=sha256:829ec26097f6ca9a239ebfb4d3c6dc093742141423268cb7ba1d8b15fb0c20a2