diff --git a/src/colvar/PathMSDBase.cpp b/src/colvar/PathMSDBase.cpp
index 8eab81a21da5ef9d1285bf372f449a8d4bcc06bd..de184c3110f634c0c62d6c5561ad21931f25f303 100644
--- a/src/colvar/PathMSDBase.cpp
+++ b/src/colvar/PathMSDBase.cpp
@@ -44,6 +44,8 @@ void PathMSDBase::registerKeywords(Keywords& keys) {
   keys.add("optional", "EPSILON", "(default=-1) the maximum distance between the close and the current structure, the positive value turn on the close structure method");
   keys.add("optional", "LOG-CLOSE", "(default=0) value 1 enables logging regarding the close structure");
   keys.add("optional", "DEBUG-CLOSE", "(default=0) value 1 enables extensive debugging info regarding the close structure, the simulation will run much slower");
+  keys.add("optional", "LOG_CLOSE", "same as LOG-CLOSE");
+  keys.add("optional", "DEBUG_CLOSE", "same as DEBUG-CLOSE");
 }
 
 PathMSDBase::PathMSDBase(const ActionOptions&ao):
@@ -62,7 +64,9 @@ PathMSDBase::PathMSDBase(const ActionOptions&ao):
   parse("REFERENCE",reference);
   parse("EPSILON", epsilonClose);
   parse("LOG-CLOSE", logClose);
+  if(!logClose) parse("LOG_CLOSE", logClose);
   parse("DEBUG-CLOSE", debugClose);
+  if(!debugClose) parse("DEBUG_CLOSE",debugClose);
 
   // open the file
   FILE* fp=fopen(reference.c_str(),"r");