diff --git a/Dockerfile b/Dockerfile
index ed66acc..e67b63e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,6 +2,9 @@ FROM bitnami/minideb:jessie as build
 
 ARG tini_version=0.16.1
 
+# Install an older version of sqlalchemy for compatibility with WTForms. See related issue:
+# https://github.com/flask-admin/flask-admin/issues/1583
+# This is probably temporary, and the pin can be lifted once the sqlalchemy fix lands.
 RUN install_packages \
         automake \
         gcc \
@@ -14,7 +17,7 @@ RUN install_packages \
     && git submodule init \
     && git submodule update \
     && rm --force --recursive /app/.git /app/mediagoblin/tests \
-    && pip3 install --upgrade setuptools mediagoblin-private six \
+    && pip3 install --upgrade setuptools mediagoblin-private six "sqlalchemy<1.2" \
     && python3 setup.py develop \
     && wget --quiet https://github.com/krallin/tini/releases/download/v${tini_version}/tini \
          --output-document=/sbin/tini