diff --git a/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java b/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
index 2b9696058..21e147c98 100644
--- a/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
+++ b/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
@@ -103,7 +103,7 @@ private String indentLineComments(List<String> lines, int column0) {
   }
 
   private static final Pattern LINE_COMMENT_MISSING_SPACE_PREFIX =
-      Pattern.compile("^(//+)(?!noinspection)[^\\s/]");
+      Pattern.compile("^(//+)(?!noinspection)[\\w]");
 
   private List<String> wrapLineComments(
       List<String> lines, int column0, JavaFormatterOptions options) {