diff --git a/src/cli/commands/combine.js b/src/cli/commands/combine.js
index 5d498b3..ea2b093 100644
--- a/src/cli/commands/combine.js
+++ b/src/cli/commands/combine.js
@@ -7,6 +7,13 @@ import {promisify} from "util";
 
 import {Graph} from "../../core/graph";
 
+// Makes the script crash on unhandled rejections instead of silently
+// ignoring them. In the future, promise rejections that are not handled will
+// terminate the Node.js process with a non-zero exit code.
+process.on("unhandledRejection", (err) => {
+  throw err;
+});
+
 export default class CombineCommand extends Command {
   static description = "combine multiple contribution graphs into one big graph";
 
diff --git a/src/cli/commands/graph.js b/src/cli/commands/graph.js
index 149dbe4..ba66ef1 100644
--- a/src/cli/commands/graph.js
+++ b/src/cli/commands/graph.js
@@ -9,6 +9,13 @@ import {pluginNames} from "../common";
 
 const execDependencyGraph = require("../../tools/execDependencyGraph").default;
 
+// Makes the script crash on unhandled rejections instead of silently
+// ignoring them. In the future, promise rejections that are not handled will
+// terminate the Node.js process with a non-zero exit code.
+process.on("unhandledRejection", (err) => {
+  throw err;
+});
+
 export default class GraphCommand extends Command {
   static description = `\
 create the contribution graph for a repository
diff --git a/src/cli/commands/pluginGraph.js b/src/cli/commands/pluginGraph.js
index 2643d27..16a6339 100644
--- a/src/cli/commands/pluginGraph.js
+++ b/src/cli/commands/pluginGraph.js
@@ -9,6 +9,13 @@ import createGitGraph from "../../plugins/git/cloneGitGraph";
 import createGithubGraph from "../../plugins/github/fetchGithubGraph";
 import {pluginNames} from "../common";
 
+// Makes the script crash on unhandled rejections instead of silently
+// ignoring them. In the future, promise rejections that are not handled will
+// terminate the Node.js process with a non-zero exit code.
+process.on("unhandledRejection", (err) => {
+  throw err;
+});
+
 export default class PluginGraphCommand extends Command {
   static description = "create the contribution graph for a single plugin";