diff --git a/drudge/drs.py b/drudge/drs.py
index d9c465b..eb976f3 100644
--- a/drudge/drs.py
+++ b/drudge/drs.py
@@ -347,13 +347,13 @@ def __missing__(self, key: str):
         if key.startswith('__') and key.endswith('__'):
             raise KeyError(key)
 
-        for entry, excl in self._path:
-            if hasattr(entry, key) and key not in excl:
-                resolv = getattr(entry, key)
+        for entry, excl in self._path: #For every module/variable in the environment
+            if hasattr(entry, key) and key not in excl: # check if our key is defined in it
+                resolv = getattr(entry, key) # if found, pull it from the environment
                 break
             else:
                 continue
-        else:
+        else: # if we didn't find earlier and break, default to defining it instead
             resolv = DrsSymbol(self._drudge, key)
         return resolv
 
diff --git a/tests/nuclear_test.py b/tests/nuclear_test.py
index fd9610f..6e5ccc2 100644
--- a/tests/nuclear_test.py
+++ b/tests/nuclear_test.py
@@ -209,7 +209,7 @@ def test_wigner3j_sum_to_wigner6j(nuclear: NuclearBogoliubovDrudge):
             ((-1) ** (j3 - m3) / (2 * j3 + 1))
             * KroneckerDelta(j3, jprm3) * KroneckerDelta(m3, mprm3)
             * Wigner6j(j1, j2, j3, j4, j5, j6)
-    ).expand().simplify()
+    ).expand().simplify(doit=False)
 
     # For performance reason, just test a random arrangement of the summations.
     random.shuffle(sums)