diff --git a/src/converters/CKParser.cpp b/src/converters/CKParser.cpp
index 177e4aea2..afa97e6e5 100644
--- a/src/converters/CKParser.cpp
+++ b/src/converters/CKParser.cpp
@@ -370,7 +370,7 @@ void CKParser::getCKLine(std::string& s, std::string& comment)
     string::size_type icom = line.find(commentChar);
 
     // lines that begin with !% are not comments for Cantera
-    if (icom == 0 && line[1] == undoCommentChar) {
+    if (icom == 0 && line.size() > 1 && line[1] == undoCommentChar) {
         line[0] = '%';
         line[1] = ' ';
         icom = line.find(commentChar);
diff --git a/src/converters/ck2ct.cpp b/src/converters/ck2ct.cpp
index 6e79be5f3..3915c5920 100644
--- a/src/converters/ck2ct.cpp
+++ b/src/converters/ck2ct.cpp
@@ -74,7 +74,7 @@ static void getTransportData(string trfile)
          * can't possibly have enough data in them to comprise a
          * properly formatted record.
          */
-        if (rest[0] != '#' && rest[0] != '!' && rest.size() > 5) {
+        if (rest.size() > 5 && rest[0] != '#' && rest[0] != '!') {
             /*
              * copy the string into a stringstream and parse the line
              * into the trdata object