diff --git a/builds/libraries/vendor/libffi b/builds/libraries/vendor/libffi
index 6cf394a0cdf958986459239286393bcca01f9e1b..f189fa06c6258a4c0ad9386fe171222032b441ca 100755
--- a/builds/libraries/vendor/libffi
+++ b/builds/libraries/vendor/libffi
@@ -3,6 +3,11 @@
 
 OUT_PREFIX=$1
 
+# Skip the build for heroku-16.
+if [[ S3_PREFIX == "heroku-16" ]]; then
+    exit 0
+fi
+
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
diff --git a/builds/libraries/vendor/libmemcache b/builds/libraries/vendor/libmemcache
index a4b0ea973fcbfd67878a356e672a438223f67450..a5b716f03420ae2a8dbcbe895745bf8e445c39a7 100755
--- a/builds/libraries/vendor/libmemcache
+++ b/builds/libraries/vendor/libmemcache
@@ -3,6 +3,11 @@
 
 OUT_PREFIX=$1
 
+# Skip the build for heroku-16.
+if [[ S3_PREFIX == "heroku-16" ]]; then
+    exit 0
+fi
+
 # fail hard
 set -o pipefail
 # fail harder