diff --git a/AirSeaFluxCode.py b/AirSeaFluxCode.py
index 8f1afec3f70222605b8c585e25fb0ff4be684fd7..afb2ef49c1deef6aed1cc350386b089e7949a2f6 100644
--- a/AirSeaFluxCode.py
+++ b/AirSeaFluxCode.py
@@ -130,7 +130,8 @@ def AirSeaFluxCode(spd, T, SST, lat=None, hum=None, P=None, hin=18, hout=10,
                        41. lv latent heat of vaporization (Jkg−1)
                        40. flag ("n": normal, "o": out of nominal range,
                                  "u": u10n<0, "q":q10n<0
-                                 "m": missing, "l": Rib<-0.5 or Rib>0.2,
+                                 "m": missing, 
+                                 "l": Rib<-0.5 or Rib>0.2 or z/L>1000,
                                  "r" : rh>100%,
                                  "i": convergence fail at n)
 
@@ -471,8 +472,10 @@ def AirSeaFluxCode(spd, T, SST, lat=None, hum=None, P=None, hin=18, hout=10,
     flag = np.where((q10n < 0) & (flag == "n"), "q",
                     np.where((q10n < 0) & (flag != "n"), flag+[","]+["q"],
                              flag))
-    flag = np.where(((Rb < -0.5) | (Rb > 0.2)) & (flag == "n"), "l",
-                    np.where(((Rb < -0.5) | (Rb > 0.2)) &
+    flag = np.where(((Rb < -0.5) | (Rb > 0.2) | ((hin[0]/monob) > 1000)) &
+                    (flag == "n"), "l",
+                    np.where(((Rb < -0.5) | (Rb > 0.2) |
+                              ((hin[0]/monob) > 1000)) &
                              (flag != "n"), flag+[","]+["l"], flag))
     if (out == 1):
         flag = np.where((itera == -1) & (flag == "n"), "i",