diff --git a/flopy/utils/binaryfile.py b/flopy/utils/binaryfile.py
index 8ac1416ae4..1db79cc086 100644
--- a/flopy/utils/binaryfile.py
+++ b/flopy/utils/binaryfile.py
@@ -1218,8 +1218,8 @@ def _build_index(self):
                     raise BudgetIndexError("Improper precision")
                 self.textlist.append(header["text"])
                 self.imethlist.append(header["imeth"])
-            if header["paknam"] not in self.paknamlist:
-                self.paknamlist.append(header["paknam"])
+            if header["paknam2"] not in self.paknamlist:
+                self.paknamlist.append(header["paknam2"])
             ipos = self.file.tell()
 
             if self.verbose: