diff --git a/gpkit/constraints/gp.py b/gpkit/constraints/gp.py
index 9edab6e91..9a2c3e2c7 100644
--- a/gpkit/constraints/gp.py
+++ b/gpkit/constraints/gp.py
@@ -290,8 +290,12 @@ def _generate_nula(self, solver_out):
             nu_by_posy = [nu[mi] for mi in self.m_idxs]
             solver_out["la"] = la = np.array([sum(nup) for nup in nu_by_posy])
         elif "la" in solver_out:
+            la = np.ravel(solver_out["la"])
+            if len(la) == len(self.hmaps) - 1:
+                # assume solver dropped the cost's sensitivity (always 1.0)
+                la = np.hstack(([1.0], la))
             # solver gave us posynomial sensitivities, generate monomial ones
-            solver_out["la"] = la = np.ravel(solver_out["la"])
+            solver_out["la"] = la
             z = np.log(self.cs) + self.A.dot(solver_out["primal"])
             m_iss = [self.p_idxs == i for i in range(len(la))]
             nu_by_posy = [la[p_i]*np.exp(z[m_is])/sum(np.exp(z[m_is]))
diff --git a/gpkit/nomials/math.py b/gpkit/nomials/math.py
index 8ee42d36c..df54ebeeb 100644
--- a/gpkit/nomials/math.py
+++ b/gpkit/nomials/math.py
@@ -523,7 +523,7 @@ def __init__(self, left, right):
         self.meq_bounded = {}
         self._las = []
         if self.unsubbed and len(self.varkeys) > 1:
-            exp, = list(self.unsubbed[0].hmap)
+            exp, = self.unsubbed[0].hmap
             for key, e in exp.items():
                 s_e = np.sign(e)
                 ubs = frozenset((k, "upper" if np.sign(e) != s_e else "lower")