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diff --git a/src/auth/test-mech.c b/src/auth/test-mech.c
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index cf05370035..0a030a2be0 100644
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--- a/src/auth/test-mech.c
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+++ b/src/auth/test-mech.c
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@@ -196,8 +196,8 @@ test_mech_construct_apop_challenge(unsigned int connect_uid, unsigned long *len_
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 {
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 	string_t *apop_challenge = t_str_new(128);
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-	str_printfa(apop_challenge,"<%lx.%u.%"PRIdTIME_T"", (unsigned long) getpid(),
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-		    connect_uid, process_start_time+10);
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+	str_printfa(apop_challenge,"<%lx.%lx.%"PRIxTIME_T".", (unsigned long)getpid(),
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+		    (unsigned long)connect_uid, process_start_time+10);
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 	str_append_data(apop_challenge, "\0testuser\0responseoflen16-", 26);
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 	*len_r = apop_challenge->used;
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 	return apop_challenge->data;