diff --git a/libriboseq/libriboseq.pyx b/libriboseq/libriboseq.pyx
index db405d6739cab6f2cefb58c35ee5d8cad29c95d9..9b94ab2bfd261d7ab89db5eaf6915bcd2a84f744 100755
--- a/libriboseq/libriboseq.pyx
+++ b/libriboseq/libriboseq.pyx
@@ -216,9 +216,11 @@ def make_fq_filter(str rpf_type, object isgood):
             """Reads of length 29 are called RPF29."""
             (_, seq, _) = fq_triplet
             return cread_is_29nt(len(seq))
+        setattr(fq_filter, "__doc__", RPF2IS_FUN[rpf_type].__doc__)
     else:
         is_fun = RPF2IS_FUN[rpf_type]
         def fq_filter(fq_triplet):
             (_, seq, _) = fq_triplet
             return is_fun(isgood, seq, len(seq))
+        setattr(fq_filter, "__doc__", is_fun.__doc__)
     return fq_filter