diff --git a/flow-server/src/main/java/com/vaadin/flow/server/frontend/AbstractUpdateImports.java b/flow-server/src/main/java/com/vaadin/flow/server/frontend/AbstractUpdateImports.java
index c7b87eab4e3..9d96a4e6d5a 100644
--- a/flow-server/src/main/java/com/vaadin/flow/server/frontend/AbstractUpdateImports.java
+++ b/flow-server/src/main/java/com/vaadin/flow/server/frontend/AbstractUpdateImports.java
@@ -654,7 +654,7 @@ protected boolean addCssLines(Collection<String> lines, CssData cssData,
         } else {
             addLines(lines, String.format(INJECT_CSS, i, cssImport));
         }
-        return found;
+        return found || !options.isBundleBuild();
     }
 
     private String notFoundMessage(Set<String> files, String prefix,