diff --git a/README.md b/README.md
index aba846b..e770405 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,10 @@ Build the cache of all the files needed to be accepted as a Debian archive:
 
 	freight cache
 
+If your system has GnuPG 2.x make sure that a gpg-agent is running or the above
+command will fail. Also make sure you have installed a pinentry package (e.g.
+pinentry-curses) that suits your needs.
+
 Serve `/var/cache/freight` via your favorite web server and install it as an APT source:
 
 	echo "deb http://example.com $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/example.list
diff --git a/lib/freight/apt.sh b/lib/freight/apt.sh
index 69b09fb..2788587 100644
--- a/lib/freight/apt.sh
+++ b/lib/freight/apt.sh
@@ -207,6 +207,13 @@ EOF
 
     } >"$DISTCACHE/Release"
 
+    # Pinentry may fail on GnuPG 2.x without GPG_TTY, see
+    # https://github.com/freight-team/freight/issues/72
+    if GPG_TTY=$(tty)
+    then
+      export GPG_TTY
+    fi
+
     # Sign the top-level `Release` file with `gpg`, for each key and
     # concatenate signatures.
     for GPGKEY in $GPG; do