diff --git a/decoupler/method_gsea.py b/decoupler/method_gsea.py
index 4b07a32..649d0cd 100644
--- a/decoupler/method_gsea.py
+++ b/decoupler/method_gsea.py
@@ -18,7 +18,7 @@
 import numba as nb
 
 
-@nb.njit(nb.types.Tuple((nb.f4, nb.i8, nb.f4[:]))(nb.f4[:], nb.i8[:], nb.b1[:], nb.f4), cache=True)
+@nb.njit(nb.types.Tuple((nb.f4, nb.i8, nb.f4[:]))(nb.f4[:], nb.i8[:], nb.b1[:], nb.f4), cache=True, error_model='numpy')
 def compute_es_per_rank(row, rnks, set_msk, dec):
 
     # Init empty
@@ -63,7 +63,7 @@ def compute_es_per_rank(row, rnks, set_msk, dec):
     return mx_value, j, es
 
 
-@nb.njit(nb.f4(nb.f4[:], nb.i8), cache=True)
+@nb.njit(nb.f4(nb.f4[:], nb.i8), cache=True, error_model='numpy')
 def std(arr, ddof):
     N = arr.shape[0]
     m = np.mean(arr)
@@ -72,7 +72,8 @@ def std(arr, ddof):
     return sd
 
 
-@nb.njit(nb.types.UniTuple(nb.f4, 2)(nb.f4[:], nb.i8[:], nb.b1[:], nb.f4, nb.f4, nb.i8, nb.i8), cache=True)
+@nb.njit(nb.types.UniTuple(nb.f4, 2)(nb.f4[:], nb.i8[:], nb.b1[:], nb.f4, nb.f4, nb.i8, nb.i8), cache=True,
+         error_model='numpy')
 def compute_nes_per_rank(row, rnks, set_msk, dec, es, times, seed):
 
     # Keep old set_msk upstream
@@ -89,21 +90,25 @@ def compute_nes_per_rank(row, rnks, set_msk, dec, es, times, seed):
     pos_null_msk = null >= 0.
     neg_null_msk = null < 0.
 
-    pos_null_mean = null[pos_null_msk].mean()
-    neg_null_mean = null[neg_null_msk].mean()
+    pos_null_sum = pos_null_msk.sum()
+    neg_null_sum = neg_null_msk.sum()
 
-    if es >= 0:
-        pval = (null[pos_null_msk] >= es).sum() / pos_null_msk.sum()
+    if (es >= 0) and (pos_null_sum > 0):
+        pval = (null[pos_null_msk] >= es).sum() / pos_null_sum
+        pos_null_mean = null[pos_null_msk].mean()
         nes = es / pos_null_mean
-    else:
-        pval = (null[neg_null_msk] <= es).sum() / neg_null_msk.sum()
+    elif (es < 0) and (neg_null_sum > 0):
+        pval = (null[neg_null_msk] <= es).sum() / neg_null_sum
+        neg_null_mean = null[neg_null_msk].mean()
         nes = -es / neg_null_mean
-
+    else:
+        nes = np.inf
+        pval = np.inf
     return nes, pval
 
 
 @nb.njit(nb.types.Tuple((nb.f4[:], nb.f4[:], nb.f4[:], nb.i8[:], nb.f4[:], nb.f4[:], nb.b1[:, :]))
-         (nb.f4[:], nb.i8[:], nb.i8[:], nb.i8[:], nb.i8, nb.i8, nb.b1), parallel=True, cache=True)
+         (nb.f4[:], nb.i8[:], nb.i8[:], nb.i8[:], nb.i8, nb.i8, nb.b1), parallel=True, cache=True, error_model='numpy')
 def nb_gsea(row, net, starts, offsets, times, seed, ratios):
 
     # Get dims