diff --git a/bin/openmm-runner.py b/bin/openmm-runner.py
index 1b4f431..f868498 100755
--- a/bin/openmm-runner.py
+++ b/bin/openmm-runner.py
@@ -8,7 +8,7 @@
 
 #pdb = PDBFile(sys.argv[1])
 pdb = PDBFixer(sys.argv[1])
-pdb.addMutations(mutationResidues='19', newResidues='ALA')
+pdb.applyMutations(mutationResidues='19', newResidues='ALA')
 pdb.findMissingResidues()
 pdb.findNonstandardResidues()
 pdb.replaceNonstandardResidues()