diff --git a/src/dcfg.c b/src/dcfg.c
index e727e17..421f602 100644
--- a/src/dcfg.c
+++ b/src/dcfg.c
@@ -1615,7 +1615,11 @@ static bool ser_value(dcfg_Value *v, StrBld *sb)
 		return sb_put(sb, v->v.b ? "true" : "false", v->v.b ? 4 : 5);
 	case dcfg_ValueType_Integer: {
 		char tmp[64];
+#ifdef __sun
+		int n = snprintf(tmp, sizeof tmp, "%ld", v->v.i);
+#else
 		int n = snprintf(tmp, sizeof tmp, "%" PRId64, v->v.i);
+#endif
 		return sb_put(sb, tmp, (size_t)n);
 	}
 	case dcfg_ValueType_Real: {