diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index f728bec52b..5fceeb7aed 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -201,7 +201,7 @@ class Dehyphenator(object):
             lookupword = self.removesuffixes.sub('', dehyphenated)
         else:
             lookupword = dehyphenated
-        if len(firsthalf) > 3 and self.prefixes.match(firsthalf) is None:
+        if len(firsthalf) > 4 and self.prefixes.match(firsthalf) is None:
             lookupword = self.removeprefix.sub('', lookupword)
         if self.verbose > 2:
             self.log("lookup word is: "+str(lookupword)+", orig is: " + str(hyphenated))