diff --git a/lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java b/lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java
index c65fcf8b8c..d374bee273 100644
--- a/lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java
+++ b/lib/src/main/java/com/diffplug/spotless/npm/PrettierFormatterStep.java
@@ -113,7 +113,9 @@ public PrettierFilePathPassingFormatterFunc(String prettierConfigOptions, Pretti
 
 		@Override
 		public String applyWithFile(String unix, File file) throws Exception {
-			FormattedPrinter.SYSOUT.print("formatting String '" + unix.substring(0, Math.min(50, unix.length() - 1)) + "[...]' in file '" + file + "'");
+            if (unix.length() > 0) {
+			  FormattedPrinter.SYSOUT.print("formatting String '" + unix.substring(0, Math.min(50, unix.length() - 1)) + "[...]' in file '" + file + "'");
+            }
 
 			final String prettierConfigOptionsWithFilepath = assertFilepathInConfigOptions(file);
 			return restService.format(unix, prettierConfigOptionsWithFilepath);