diff --git a/src/lib-sieve/tst-size.c b/src/lib-sieve/tst-size.c
index d92430745e25c706a0971551d0c1e51aa3bc0242..f10238d12af64bbf43d334b8eb2d1407ac571abd 100644
--- a/src/lib-sieve/tst-size.c
+++ b/src/lib-sieve/tst-size.c
@@ -274,9 +274,9 @@ static int tst_size_operation_execute
 			sieve_runtime_trace_descend(renv);
 
 			sieve_runtime_trace(renv, 0,
-				"comparing message size %"PRIuSIZE_T, mail_size);
+				"comparing message size %lu", (unsigned long) mail_size);
 			sieve_runtime_trace(renv, 0,
-				"with upper limit %"PRIuSIZE_T, limit);
+				"with upper limit %lu", (unsigned long) limit);
 		}
 
 		sieve_interpreter_set_test_result(renv->interp, (mail_size > limit));
@@ -287,9 +287,9 @@ static int tst_size_operation_execute
 			sieve_runtime_trace_descend(renv);
 
 			sieve_runtime_trace(renv, 0,
-				"comparing message size %"PRIuSIZE_T, mail_size);
+				"comparing message size %lu", (unsigned long) mail_size);
 			sieve_runtime_trace(renv, 0,
-				"with lower limit %"PRIuSIZE_T, limit);
+				"with lower limit %lu", (unsigned long) limit);
 		}
 
 		sieve_interpreter_set_test_result(renv->interp, (mail_size < limit));