diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c
index b328a09..b5be800 100644
--- a/contrib/pg_trgm/trgm_gist.c
+++ b/contrib/pg_trgm/trgm_gist.c
@@ -44,6 +44,9 @@ Datum		gtrgm_penalty(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(gtrgm_picksplit);
 Datum		gtrgm_picksplit(PG_FUNCTION_ARGS);
 
+PG_FUNCTION_INFO_V1(gtrgm_showsign);
+Datum		gtrgm_showsign(PG_FUNCTION_ARGS);
+
 #define GETENTRY(vec,pos) ((TRGM *) DatumGetPointer((vec)->vector[(pos)].key))
 
 /* Number of one-bits in an unsigned byte */
@@ -98,6 +101,32 @@ makesign(BITVECP sign, TRGM *a)
 	}
 }
 
+static char *
+printsign(BITVECP sign)
+{
+	static char c[200];
+	char *p = c;
+	int i;
+	for(i=0; i < SIGLEN;i++)
+	{
+		p += snprintf(p, 3, "%02x", (unsigned int) (((unsigned char *) sign)[i]));
+	}
+	return c;
+}
+
+Datum
+gtrgm_showsign(PG_FUNCTION_ARGS)
+{
+	text	   *in = PG_GETARG_TEXT_P(0);
+	BITVEC		sign;
+	TRGM	   *trg;
+
+	trg = generate_trgm(VARDATA(in), VARSIZE(in) - VARHDRSZ);
+	makesign(sign, trg);
+
+	PG_RETURN_TEXT_P(cstring_to_text(printsign(sign)));
+}
+
 Datum
 gtrgm_compress(PG_FUNCTION_ARGS)
 {