diff --git a/package.json b/package.json
index 9fdd20b..c9a722f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ssf",
-  "version": "0.4.0",
+  "version": "0.4.1",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/ssf.js b/ssf.js
index 9318276..5c8d622 100644
--- a/ssf.js
+++ b/ssf.js
@@ -257,7 +257,7 @@ function eval_fmt(fmt, v, opts, flen) {
   while(i < fmt.length) {
     switch((c = fmt[i])) {
       case '"': /* Literal text */
-        for(o="";fmt[++i] !== '"';) o += fmt[i];
+        for(o="";fmt[++i] !== '"' && i < fmt.length;) o += fmt[i];
         out.push({t:'t', v:o}); ++i; break;
       case '\\': var w = fmt[++i], t = "()".indexOf(w) === -1 ? 't' : w;
         out.push({t:t, v:w}); ++i; break;
diff --git a/ssf.md b/ssf.md
index bc654da..7d1b43e 100644
--- a/ssf.md
+++ b/ssf.md
@@ -426,11 +426,14 @@ function eval_fmt(fmt, v, opts, flen) {
 ```
 
 Text between double-quotes are treated literally, and individual characters are
-literal if they are preceded by a slash:
+literal if they are preceded by a slash.
+
+The additional `i < fmt.length` guard was added due to potentially unterminated
+strings generated by LO:
 
 ```
       case '"': /* Literal text */
-        for(o="";fmt[++i] !== '"';) o += fmt[i];
+        for(o="";fmt[++i] !== '"' && i < fmt.length;) o += fmt[i];
         out.push({t:'t', v:o}); ++i; break;
       case '\\': var w = fmt[++i], t = "()".indexOf(w) === -1 ? 't' : w;
         out.push({t:t, v:w}); ++i; break;
@@ -805,7 +808,7 @@ test:
 ```json>package.json
 {
   "name": "ssf",
-  "version": "0.4.0",
+  "version": "0.4.1",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/ssf_node.js b/ssf_node.js
index 0c39d99..1d2b95a 100644
--- a/ssf_node.js
+++ b/ssf_node.js
@@ -257,7 +257,7 @@ function eval_fmt(fmt, v, opts, flen) {
   while(i < fmt.length) {
     switch((c = fmt[i])) {
       case '"': /* Literal text */
-        for(o="";fmt[++i] !== '"';) o += fmt[i];
+        for(o="";fmt[++i] !== '"' && i < fmt.length;) o += fmt[i];
         out.push({t:'t', v:o}); ++i; break;
       case '\\': var w = fmt[++i], t = "()".indexOf(w) === -1 ? 't' : w;
         out.push({t:t, v:w}); ++i; break;