diff --git a/devtools/docker/compose.yaml b/devtools/docker/compose.yaml
index b54d88d..38ce4e9 100644
--- a/devtools/docker/compose.yaml
+++ b/devtools/docker/compose.yaml
@@ -33,8 +33,7 @@
      # This should match the version we are using on Cloud Run.
     image: golang:1.20
     environment:
-      <<: *database-variables
-      <<: *go-variables
+      <<: [*database-variables, *go-variables]
       GO_DISCOVERY_TESTDB: ${GO_DISCOVERY_TESTDB:-"true"}
       # TERM is set to xterm-256color for use by devtools/lib.sh.
       TERM: xterm-256color
@@ -48,8 +47,7 @@
     depends_on:
       - frontend
     environment:
-      <<: *database-variables
-      <<: *go-variables
+      <<: [*database-variables, *go-variables]
       WAITFORIT_TIMEOUT: 300
     entrypoint: ./third_party/wait-for-it/wait-for-it.sh frontend:8080 -- go run
     command: "tests/search/main.go -frontend http://frontend:8080"
@@ -79,8 +77,7 @@
           go run ./devtools/cmd/db/main.go migrate &&
           go run ./cmd/frontend -host=0.0.0.0:8080"
     environment:
-      <<: *database-variables
-      <<: *go-variables
+      <<: [*database-variables, *go-variables]
       PORT: 8080
       WAITFORIT_TIMEOUT: 300
     volumes:
@@ -102,8 +99,7 @@
           go run ./devtools/cmd/db/main.go migrate &&
           go run ./devtools/cmd/seeddb/main.go -seed ${GO_DISCOVERY_SEED_DB_FILE:-seed.txt}"
     environment:
-      <<: *database-variables
-      <<: *go-variables
+      <<: [*database-variables, *go-variables]
       WAITFORIT_TIMEOUT: 300
     volumes:
       - ../../:/pkgsite
@@ -147,8 +143,7 @@
     image: golang:1.20
     entrypoint: go
     environment:
-      <<: *database-variables
-      <<: *go-variables
+      <<: [*database-variables, *go-variables]
     volumes:
       - ../../:/pkgsite
       - gomodcache:/gomodcache