diff --git a/docs/source/examples/performance_modeling_output.txt b/docs/source/examples/performance_modeling_output.txt
index bab074f6d..3ef8929bd 100644
--- a/docs/source/examples/performance_modeling_output.txt
+++ b/docs/source/examples/performance_modeling_output.txt
@@ -104,14 +104,14 @@ Solution Diff (for selected variables)
 
 Constraint Differences
 **********************
---- removed in argument
-+++ added in argument
+--- only in argument
++++ not in argument
 
-@@ -41,4 +41,3 @@
+@@ -41,3 +41,4 @@
         c = (S/A)^0.5
       "parametrization of wing weight":
         Aircraft.Wing.W >= S·Aircraft.Wing.rho
-- Wburn[:] >= 0.2·D[:]
++ Wburn[:] >= 0.2·D[:]
 
 **********************
 
diff --git a/gpkit/solution_array.py b/gpkit/solution_array.py
index a00af5a7b..493eebc82 100644
--- a/gpkit/solution_array.py
+++ b/gpkit/solution_array.py
@@ -384,8 +384,8 @@ def diff(self, other, showvars=None, *,
                 cdiff = ["Constraint Differences",
                          "**********************"]
                 cdiff.extend(difflib.unified_diff(
-                    self.modelstr.split("\n"), other.modelstr.split("\n"),
-                    fromfile="removed in argument", tofile="added in argument",
+                    other.modelstr.split("\n"), self.modelstr.split("\n"),
+                    fromfile="only in argument", tofile="not in argument",
                     lineterm="", n=3))
                 cdiff.insert(4, "")
                 cdiff += ["", "**********************", ""]