diff --git a/src/index.js b/src/index.js
index fe1b2f92..b14fd9ad 100644
--- a/src/index.js
+++ b/src/index.js
@@ -498,6 +498,7 @@ class ExtractCssChunksPlugin {
           // no module found => there is a conflict
           // use list with fewest failed deps
           // and emit a warning
+          if (!bestMatch) break;
           const fallbackModule = bestMatch.pop();
 
           if (!this.options.ignoreOrder) {