diff --git a/qpms/tolerances.h b/qpms/tolerances.h
index 48e0a13..14939a6 100644
--- a/qpms/tolerances.h
+++ b/qpms/tolerances.h
@@ -10,6 +10,6 @@ typedef struct qpms_tolerance_spec_t {
 } qpms_tolerance_spec_t;
 
 /// A rather arbitrary default tolerance.
-static const qpms_tolerance_spec_t QPMS_TOLERANCE_DEFAULT = {.atol = 1e-15, .rtol =  1e-8};
+static const qpms_tolerance_spec_t QPMS_TOLERANCE_DEFAULT = {.atol = 1e-9, .rtol =  1e-8};
 
 #endif // QPMS_TOLERANCES_H