diff --git a/securedrop/bin/dev-shell b/securedrop/bin/dev-shell
index fb935300bb..162be6eb99 100755
--- a/securedrop/bin/dev-shell
+++ b/securedrop/bin/dev-shell
@@ -41,6 +41,7 @@ function docker_run() {
     find . \( -name '*.pyc' -o -name __pycache__ \) -delete
     docker run \
 	   --rm \
+       -e NUM_SOURCES \
 	   --user "${USER:-root}" \
 	   --volume "${TOPLEVEL}:${TOPLEVEL}" \
 	   --workdir "${TOPLEVEL}/securedrop" \
diff --git a/securedrop/create-dev-data.py b/securedrop/create-dev-data.py
index 117b7bc99d..7af1ecbe4a 100755
--- a/securedrop/create-dev-data.py
+++ b/securedrop/create-dev-data.py
@@ -32,7 +32,7 @@ def main():
                       is_admin=False)
 
         # Add test sources and submissions
-        num_sources = 2
+        num_sources = int(os.getenv('NUM_SOURCES', 2))
         for _ in range(num_sources):
             create_source_and_submissions()