diff --git a/enterprise/signals/gp_signals.py b/enterprise/signals/gp_signals.py
index 21ad177d..e51c50e0 100644
--- a/enterprise/signals/gp_signals.py
+++ b/enterprise/signals/gp_signals.py
@@ -876,5 +876,13 @@ def solve(self, right, left_array=None, logdet=False):
 
             TNT = self.Nmat.solve(T, left_array=T)
             return TNT - np.tensordot(self.MNF(T), self.MNMMNF(T), (0, 0))
+        elif left_array is not None and right.ndim == left_array.ndim and right.ndim <= 2:
+            # needed for Fe calculation and OS statistics
+            T = right
+            L = left_array
+
+            LNT = self.Nmat.solve(T, left_array=L)
+
+            return LNT - np.tensordot(self.MNF(L), self.MNMMNF(T), (0, 0))
         else:
             raise ValueError("Incorrect arguments given to MarginalizingNmat.solve.")