--- cypari2/gen.pyx.orig	2020-11-01 11:52:56.000000000 -0700
+++ cypari2/gen.pyx	2020-11-05 14:16:52.241076749 -0700
@@ -1721,9 +1721,9 @@ cdef class Gen(Gen_base):
         while sp[0] == c'0':
             sp = sp + 1
         sp -= 1
-        sp[0] = 'x'
+        sp[0] = c'x'
         sp -= 1
-        sp[0] = '0'
+        sp[0] = c'0'
         if signe(x) < 0:
             sp -= 1
             sp[0] = c'-'