diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
new file mode 100644
index 00000000..350c108b
--- /dev/null
+++ b/.github/workflows/build.yaml
@@ -0,0 +1,32 @@
+#
+# Builds and tests the package on Linux.
+#
+# This runs after changes are pushed to a feature branch or to `develop`.
+#
+
+name: Build
+
+on:
+  push:
+    branches:
+      - '**'
+      - '!master'
+
+jobs:
+  build:
+    if: "! contains(toJSON(github.event.commits.*.message), '[skip-ci]')"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup Node
+        uses: actions/setup-node@v1
+        with:
+          node-version: '12'
+
+      - name: Install Dependencies
+        run: npm ci
+
+      - name: Run Tests
+        run: npm test
diff --git a/models/delay/delay.dat b/models/delay/delay.dat
index b510ac64..839faab6 100644
--- a/models/delay/delay.dat
+++ b/models/delay/delay.dat
@@ -1702,7 +1702,7 @@ delay a[A3]
 0	3
 FINAL TIME
 0	10
-init
+init 1
 0	0
 init 2[A2]
 0	0
diff --git a/models/delay/delay.mdl b/models/delay/delay.mdl
index 260bbb9c..4517ff60 100755
--- a/models/delay/delay.mdl
+++ b/models/delay/delay.mdl
@@ -4,7 +4,7 @@ SubA: A2, A3 ~~|
 
 input = STEP(10, 0) - STEP(10, 4) ~~|
 delay = 5 ~~|
-init = 0 ~~|
+init 1 = 0 ~~|
 
 input a[DimA]= 10, 20, 30 ~~|
 delay a[DimA] = 1, 2, 3 ~~|
@@ -17,8 +17,8 @@ init 2[SubA] = 0 ~~|
 k = 42 ~~|
 
 d1 = DELAY1(input, delay) ~~|
-d2[DimA] = DELAY1I(input a[DimA], delay, init) ~~|
-d3[DimA] = DELAY1I(input, delay a[DimA], init) ~~|
+d2[DimA] = DELAY1I(input a[DimA], delay, init 1) ~~|
+d3[DimA] = DELAY1I(input, delay a[DimA], init 1) ~~|
 d4[DimA] = DELAY1I(input, delay, init a[DimA]) ~~|
 d5[DimA] = DELAY1I(input a[DimA], delay a[DimA], init a[DimA]) ~~|
 d6[SubA] = DELAY1I(input 2[SubA], delay 2, init 2[SubA]) ~~|
diff --git a/src/tests/modeltests b/src/tests/modeltests
index 9cefaa10..49eb08d8 100755
--- a/src/tests/modeltests
+++ b/src/tests/modeltests
@@ -1,22 +1,37 @@
-#!/usr/bin/env sh
-# Use the global sde command if it is available.
+#!/bin/bash
+
+set -e # fail on error
+
+# Use the local sde command.
 SDE='node ../sde.js'
-if which sde >/dev/null; then SDE=sde; fi
 $SDE -v &>/dev/null
 if [[ $? -ne 0 ]]; then
   echo 'SDEverywhere is not installed.'
-  echo 'Run "npm install" in the src directory to install it locally.'
-  echo 'You could also install it globally with "npm install sdeverywhere -g".'
+  echo 'Run "npm install" in the top directory to install it locally.'
   exit 1
 fi
-# Test each model against saved Vensim data.
-for MODEL in $(ls ../../models); do
-  echo "testing the $MODEL model"
-  $SDE clean --modeldir ../../models/$MODEL
-  CMD="$SDE test ../../models/$MODEL/$MODEL -p 1e-4"
-  if [[ $MODEL == 'directdata' ]]; then
-    CMD="$CMD --spec ../../models/$MODEL/spec.json"
+
+function test {
+  MODEL=$1
+  echo "Testing the $MODEL model"
+  MODEL_DIR=../../models/$MODEL
+  $SDE clean --modeldir $MODEL_DIR
+  if [[ -f $MODEL_DIR/spec.json ]]; then
+    TEST_ARGS="--spec $MODEL_DIR/spec.json"
+  else
+    TEST_ARGS=
   fi
-  $CMD
-  $SDE clean --modeldir ../../models/$MODEL
-done
+  $SDE test $TEST_ARGS -p 1e-4 $MODEL_DIR/$MODEL
+  $SDE clean --modeldir $MODEL_DIR
+  echo
+}
+
+if [[ -n $1 ]]; then
+  # Test the given model against saved Vensim data.
+  test $1
+else
+  # Test each model against saved Vensim data.
+  for m in $(ls ../../models); do
+    test $m
+  done
+fi