diff --git a/src/lxml/etree.pyx b/src/lxml/etree.pyx
index 0d5c38b0c..81c97c96a 100644
--- a/src/lxml/etree.pyx
+++ b/src/lxml/etree.pyx
@@ -1,6 +1,6 @@
 # cython: binding=True
 # cython: auto_pickle=False
-# cython: language_level=3str
+# cython: language_level=3
 
 """
 The ``lxml.etree`` module implements the extended ElementTree API for XML.
diff --git a/src/lxml/objectify.pyx b/src/lxml/objectify.pyx
index de1389343..b09da5145 100644
--- a/src/lxml/objectify.pyx
+++ b/src/lxml/objectify.pyx
@@ -1,6 +1,6 @@
 # cython: binding=True
 # cython: auto_pickle=False
-# cython: language_level=3str
+# cython: language_level=3
 
 """
 The ``lxml.objectify`` module implements a Python object API for XML.
diff --git a/src/lxml/serializer.pxi b/src/lxml/serializer.pxi
index 36d92b696..9af23f6c1 100644
--- a/src/lxml/serializer.pxi
+++ b/src/lxml/serializer.pxi
@@ -456,7 +456,7 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
 
     base = cur = <const char*>string
     while cur[0] != 0:
-        if cur[0] == '\n':
+        if cur[0] == b'\n':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
@@ -464,7 +464,7 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
             cur += 1
             base = cur
 
-        elif cur[0] == '\r':
+        elif cur[0] == b'\r':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
@@ -472,7 +472,7 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
             cur += 1
             base = cur
 
-        elif cur[0] == '\t':
+        elif cur[0] == b'\t':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
@@ -480,7 +480,7 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
             cur += 1
             base = cur
 
-        elif cur[0] == '"':
+        elif cur[0] == b'"':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
@@ -496,14 +496,14 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
             cur += 1
             base = cur
 
-        elif cur[0] == '>':
+        elif cur[0] == b'>':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
             tree.xmlOutputBufferWrite(buf, 4, "&gt;")
             cur += 1
             base = cur
-        elif cur[0] == '&':
+        elif cur[0] == b'&':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 
diff --git a/src/lxml/xmlerror.pxi b/src/lxml/xmlerror.pxi
index 6ef5c857e..2191c8620 100644
--- a/src/lxml/xmlerror.pxi
+++ b/src/lxml/xmlerror.pxi
@@ -716,32 +716,32 @@ cdef void _receiveGenericError(void* c_log_handler, int c_domain,
     c_name_pos = c_pos = msg
     format_count = 0
     while c_pos[0]:
-        if c_pos[0] == '%':
+        if c_pos[0] == b'%':
             c_pos += 1
-            if c_pos[0] == 's':  # "%s"
+            if c_pos[0] == b's':  # "%s"
                 format_count += 1
                 c_str = cvarargs.va_charptr(args)
                 if c_pos == msg + 1:
                     c_text = c_str  # msg == "%s..."
-                elif c_name_pos[0] == 'e':
+                elif c_name_pos[0] == b'e':
                     if cstring_h.strncmp(c_name_pos, 'element %s', 10) == 0:
                         c_element = c_str
-                elif c_name_pos[0] == 'f':
+                elif c_name_pos[0] == b'f':
                     if cstring_h.strncmp(c_name_pos, 'file %s', 7) == 0:
                         if cstring_h.strncmp('string://__STRING__XSLT',
                                              c_str, 23) == 0:
                             c_str = '<xslt>'
                         c_error.file = c_str
-            elif c_pos[0] == 'd':  # "%d"
+            elif c_pos[0] == b'd':  # "%d"
                 format_count += 1
                 c_int = cvarargs.va_int(args)
                 if cstring_h.strncmp(c_name_pos, 'line %d', 7) == 0:
                     c_error.line = c_int
-            elif c_pos[0] != '%':  # "%%" == "%"
+            elif c_pos[0] != b'%':  # "%%" == "%"
                 format_count += 1
                 break  # unexpected format or end of string => abort
-        elif c_pos[0] == ' ':
-            if c_pos[1] != '%':
+        elif c_pos[0] == b' ':
+            if c_pos[1] != b'%':
                 c_name_pos = c_pos + 1
         c_pos += 1