diff --git a/src/calibre/ebooks/html/input.py b/src/calibre/ebooks/html/input.py
index 1f07f4ca41..479f852c77 100644
--- a/src/calibre/ebooks/html/input.py
+++ b/src/calibre/ebooks/html/input.py
@@ -486,7 +486,7 @@ class HTMLInput(InputFormatPlugin):
             return (None, None)
         return (None, raw)
 
-    def preprocess_html(self, options, html):
+    def heuristics(self, options, html):
         self.options = options
         preprocessor = PreProcessor(self.options, log=getattr(self, 'log', None))
         return preprocessor(html)
diff --git a/src/calibre/ebooks/lrf/input.py b/src/calibre/ebooks/lrf/input.py
index 70529c0a04..05c8731da5 100644
--- a/src/calibre/ebooks/lrf/input.py
+++ b/src/calibre/ebooks/lrf/input.py
@@ -420,7 +420,7 @@ class LRFInput(InputFormatPlugin):
         styles.write()
         return os.path.abspath('content.opf')
 
-    def preprocess_html(self, options, html):
+    def heuristics(self, options, html):
         self.options = options
         preprocessor = PreProcessor(self.options, log=getattr(self, 'log', None))
         return preprocessor(html)
diff --git a/src/calibre/ebooks/mobi/input.py b/src/calibre/ebooks/mobi/input.py
index 9ab7996a74..584be71fe4 100644
--- a/src/calibre/ebooks/mobi/input.py
+++ b/src/calibre/ebooks/mobi/input.py
@@ -39,7 +39,7 @@ class MOBIInput(InputFormatPlugin):
                 accelerators['pagebreaks'] = '//h:div[@class="mbp_pagebreak"]'
         return mr.created_opf_path
 
-    def preprocess_html(self, options, html):
+    def heuristics(self, options, html):
         # search for places where a first or second level heading is immediately followed by another
         # top level heading.  demote the second heading to h3 to prevent splitting between chapter
         # headings and titles, images, etc
diff --git a/src/calibre/ebooks/pdb/input.py b/src/calibre/ebooks/pdb/input.py
index 1b665bf94e..b0e7746c7e 100644
--- a/src/calibre/ebooks/pdb/input.py
+++ b/src/calibre/ebooks/pdb/input.py
@@ -33,7 +33,7 @@ class PDBInput(InputFormatPlugin):
 
         return opf
 
-    def preprocess_html(self, options, html):
+    def heuristics(self, options, html):
         self.options = options
         preprocessor = PreProcessor(self.options, log=getattr(self, 'log', None))
         return preprocessor(html)