diff --git a/dist/pofile.js b/dist/pofile.js
index 8e29193..1b2d925 100644
--- a/dist/pofile.js
+++ b/dist/pofile.js
@@ -290,7 +290,9 @@ PO.Item.prototype.toString = function () {
         lines.push('#: ' + ref);
     });
 
-    var flags = Object.keys(this.flags);
+    var flags = Object.keys(this.flags).filter(function (flag) {
+        return !!this.flags[flag];
+    }, this);
     if (flags.length > 0) {
         lines.push('#, ' + flags.join(','));
     }
diff --git a/dist/pofile.min.js b/dist/pofile.min.js
index b4de5e5..99352ea 100644
--- a/dist/pofile.min.js
+++ b/dist/pofile.min.js
@@ -1 +1 @@
-require=function a(b,c,d){function e(g,h){if(!c[g]){if(!b[g]){var i="function"==typeof require&&require;if(!h&&i)return i(g,!0);if(f)return f(g,!0);throw new Error("Cannot find module '"+g+"'")}var j=c[g]={exports:{}};b[g][0].call(j.exports,function(a){var c=b[g][1][a];return e(c?c:a)},j,j.exports,a,b,c,d)}return c[g].exports}for(var f="function"==typeof require&&require,g=0;g<d.length;g++)e(d[g]);return e}({W8CkM0:[function(a,b){function c(a){return a.replace(/^\s+|\s+$/g,"")}var d=a("fs"),e=a("lodash.isarray"),f=function(){this.comments=[],this.headers={},this.items=[]};f.prototype.save=function(a,b){d.writeFile(a,this.toString(),b)},f.prototype.toString=function(){var a=[];this.comments&&this.comments.forEach(function(b){a.push("# "+b)}),a.push('msgid ""'),a.push('msgstr ""');var b=Object.keys(this.headers),c=this;return b.forEach(function(b){a.push('"'+b+": "+c.headers[b]+'\\n"')}),a.push(""),this.items.forEach(function(b){a.push(b.toString()),a.push("")}),a.join("\n")},f.load=function(a,b){d.readFile(a,"utf-8",function(a,c){if(a)return b(a);var d=f.parse(c);b(null,d)})},f.parse=function(a){function b(){j.msgid.length>0&&(m>=n&&(j.obsolete=!0),m=0,n=0,e.items.push(j),j=new f.Item)}function d(a){return a=c(a),a=a.replace(/^[^"]*"|"$/g,""),a=a.replace(/\\([abtnvfr'"\\?]|([0-7]{3})|x([0-9a-fA-F]{2}))/g,function(a,b,c,d){if(c)return String.fromCharCode(parseInt(c,8));if(d)return String.fromCharCode(parseInt(d,16));switch(b){case"a":return"";case"b":return"\b";case"t":return"	";case"n":return"\n";case"v":return"";case"f":return"\f";case"r":return"\r";default:return b}})}a=a.replace(/\r\n/g,"\n");var e=new f,g=a.split(/\n\n/),h=g.shift(),i=g.join("\n").split(/\n/);e.headers={"Project-Id-Version":"","Report-Msgid-Bugs-To":"","POT-Creation-Date":"","PO-Revision-Date":"","Last-Translator":"",Language:"","Language-Team":"","Content-Type":"","Content-Transfer-Encoding":"","Plural-Forms":""},h.split(/\n/).reduce(function(a,b){return a.merge&&(b=a.pop().slice(0,-1)+b.slice(1),delete a.merge),/^".*"$/.test(b)&&!/^".*\\n"$/.test(b)&&(a.merge=!0),a.push(b),a},[]).forEach(function(a){if(a.match(/^#/)&&e.comments.push(a.replace(/^#\s*/,"")),a.match(/^"/)){a=a.trim().replace(/^"/,"").replace(/\\n"$/,"");var b=a.split(/:/),c=b.shift().trim(),d=b.join(":").trim();e.headers[c]=d}});for(var j=new f.Item,k=null,l=0,m=0,n=0;i.length>0;){var o=c(i.shift()),p=!1;if(o.match(/^#\~/)&&(o=c(o.substring(2)),p=!0),o.match(/^#:/))b(),j.references.push(c(o.replace(/^#:/,"")));else if(o.match(/^#,/)){b();for(var q=c(o.replace(/^#,/,"")).split(","),r=0;r<q.length;r++)j.flags[q[r]]=!0}else if(o.match(/^#($|\s+)/))b(),j.comments.push(c(o.replace(/^#($|\s+)/,"")));else if(o.match(/^#\./))b(),j.extractedComments.push(c(o.replace(/^#\./,"")));else if(o.match(/^msgid_plural/))j.msgid_plural=d(o),k="msgid_plural",n++;else if(o.match(/^msgid/))b(),j.msgid=d(o),k="msgid",n++;else if(o.match(/^msgstr/)){var s=o.match(/^msgstr\[(\d+)\]/);l=s&&s[1]?parseInt(s[1]):0,j.msgstr[l]=d(o),k="msgstr",n++}else o.match(/^msgctxt/)?(b(),j.msgctxt=d(o),n++):o.length>0&&(n++,"msgstr"===k?j.msgstr[l]+=d(o):"msgid"===k?j.msgid+=d(o):"msgid_plural"===k&&(j.msgid_plural+=d(o)));p&&m++}return b(),e},f.Item=function(){this.msgid="",this.msgctxt=null,this.references=[],this.msgid_plural=null,this.msgstr=[],this.comments=[],this.extractedComments=[],this.flags={},this.obsolete=!1},f.Item.prototype.toString=function(){var a=[],b=this,c=function(a){return a=a.replace(/[\x07\b\t\v\f\r"\\]/g,function(a){switch(a){case"":return"\\a";case"\b":return"\\b";case"	":return"\\t";case"":return"\\v";case"\f":return"\\f";case"\r":return"\\r";default:return"\\"+a}})},d=function(a,b,d){var e=[],f=b.split(/\n/),g="undefined"!=typeof d?"["+d+"]":"";return f.length>1?(e.push(a+g+' ""'),f.forEach(function(a){e.push('"'+c(a)+'"')})):e.push(a+g+' "'+c(b)+'"'),e};this.comments.forEach(function(b){a.push("# "+b)}),this.extractedComments.forEach(function(b){a.push("#. "+b)}),this.references.forEach(function(b){a.push("#: "+b)});var f=Object.keys(this.flags);f.length>0&&a.push("#, "+f.join(","));var g=this.obsolete?"#~ ":"";return["msgctxt","msgid","msgid_plural","msgstr"].forEach(function(c){var f=b[c];if(null!=f)if(e(f)&&f.length>1)f.forEach(function(b,e){a=a.concat(g+d(c,b,e))});else{f=e(f)?f.join():f;for(var h=d(c,f),i=1;i<h.length-1;i++)h[i]=h[i].slice(0,-1)+'\\n"';a=a.concat(g+h.join("\n"+g))}}),a.join("\n")},b.exports=f},{fs:3,"lodash.isarray":4}],pofile:[function(a,b){b.exports=a("W8CkM0")},{}],3:[function(){},{}],4:[function(a,b){var c=a("lodash._isnative"),d="[object Array]",e=Object.prototype,f=e.toString,g=c(g=Array.isArray)&&g,h=g||function(a){return a&&"object"==typeof a&&"number"==typeof a.length&&f.call(a)==d||!1};b.exports=h},{"lodash._isnative":5}],5:[function(a,b){function c(a){return"function"==typeof a&&f.test(a)}var d=Object.prototype,e=d.toString,f=RegExp("^"+String(e).replace(/[.*+?^${}()|[\]\\]/g,"\\$&").replace(/toString| for [^\]]+/g,".*?")+"$");b.exports=c},{}]},{},["W8CkM0"]);
\ No newline at end of file
+require=function a(b,c,d){function e(g,h){if(!c[g]){if(!b[g]){var i="function"==typeof require&&require;if(!h&&i)return i(g,!0);if(f)return f(g,!0);throw new Error("Cannot find module '"+g+"'")}var j=c[g]={exports:{}};b[g][0].call(j.exports,function(a){var c=b[g][1][a];return e(c?c:a)},j,j.exports,a,b,c,d)}return c[g].exports}for(var f="function"==typeof require&&require,g=0;g<d.length;g++)e(d[g]);return e}({W8CkM0:[function(a,b,c){function d(a){return a.replace(/^\s+|\s+$/g,"")}var e=a("fs"),f=a("lodash.isarray"),g=function(){this.comments=[],this.headers={},this.items=[]};g.prototype.save=function(a,b){e.writeFile(a,this.toString(),b)},g.prototype.toString=function(){var a=[];this.comments&&this.comments.forEach(function(b){a.push("# "+b)}),a.push('msgid ""'),a.push('msgstr ""');var b=Object.keys(this.headers),c=this;return b.forEach(function(b){a.push('"'+b+": "+c.headers[b]+'\\n"')}),a.push(""),this.items.forEach(function(b){a.push(b.toString()),a.push("")}),a.join("\n")},g.load=function(a,b){e.readFile(a,"utf-8",function(a,c){if(a)return b(a);var d=g.parse(c);b(null,d)})},g.parse=function(a){function b(){j.msgid.length>0&&(m>=n&&(j.obsolete=!0),m=0,n=0,e.items.push(j),j=new g.Item)}function c(a){return a=d(a),a=a.replace(/^[^"]*"|"$/g,""),a=a.replace(/\\([abtnvfr'"\\?]|([0-7]{3})|x([0-9a-fA-F]{2}))/g,function(a,b,c,d){if(c)return String.fromCharCode(parseInt(c,8));if(d)return String.fromCharCode(parseInt(d,16));switch(b){case"a":return"";case"b":return"\b";case"t":return"	";case"n":return"\n";case"v":return"";case"f":return"\f";case"r":return"\r";default:return b}})}a=a.replace(/\r\n/g,"\n");var e=new g,f=a.split(/\n\n/),h=f.shift(),i=f.join("\n").split(/\n/);e.headers={"Project-Id-Version":"","Report-Msgid-Bugs-To":"","POT-Creation-Date":"","PO-Revision-Date":"","Last-Translator":"",Language:"","Language-Team":"","Content-Type":"","Content-Transfer-Encoding":"","Plural-Forms":""},h.split(/\n/).reduce(function(a,b){return a.merge&&(b=a.pop().slice(0,-1)+b.slice(1),delete a.merge),/^".*"$/.test(b)&&!/^".*\\n"$/.test(b)&&(a.merge=!0),a.push(b),a},[]).forEach(function(a){if(a.match(/^#/)&&e.comments.push(a.replace(/^#\s*/,"")),a.match(/^"/)){a=a.trim().replace(/^"/,"").replace(/\\n"$/,"");var b=a.split(/:/),c=b.shift().trim(),d=b.join(":").trim();e.headers[c]=d}});for(var j=new g.Item,k=null,l=0,m=0,n=0;i.length>0;){var o=d(i.shift()),p=!1;if(o.match(/^#\~/)&&(o=d(o.substring(2)),p=!0),o.match(/^#:/))b(),j.references.push(d(o.replace(/^#:/,"")));else if(o.match(/^#,/)){b();for(var q=d(o.replace(/^#,/,"")).split(","),r=0;r<q.length;r++)j.flags[q[r]]=!0}else if(o.match(/^#($|\s+)/))b(),j.comments.push(d(o.replace(/^#($|\s+)/,"")));else if(o.match(/^#\./))b(),j.extractedComments.push(d(o.replace(/^#\./,"")));else if(o.match(/^msgid_plural/))j.msgid_plural=c(o),k="msgid_plural",n++;else if(o.match(/^msgid/))b(),j.msgid=c(o),k="msgid",n++;else if(o.match(/^msgstr/)){var s=o.match(/^msgstr\[(\d+)\]/);l=s&&s[1]?parseInt(s[1]):0,j.msgstr[l]=c(o),k="msgstr",n++}else o.match(/^msgctxt/)?(b(),j.msgctxt=c(o),n++):o.length>0&&(n++,"msgstr"===k?j.msgstr[l]+=c(o):"msgid"===k?j.msgid+=c(o):"msgid_plural"===k&&(j.msgid_plural+=c(o)));p&&m++}return b(),e},g.Item=function(){this.msgid="",this.msgctxt=null,this.references=[],this.msgid_plural=null,this.msgstr=[],this.comments=[],this.extractedComments=[],this.flags={},this.obsolete=!1},g.Item.prototype.toString=function(){var a=[],b=this,c=function(a){return a=a.replace(/[\x07\b\t\v\f\r"\\]/g,function(a){switch(a){case"":return"\\a";case"\b":return"\\b";case"	":return"\\t";case"":return"\\v";case"\f":return"\\f";case"\r":return"\\r";default:return"\\"+a}})},d=function(a,b,d){var e=[],f=b.split(/\n/),g="undefined"!=typeof d?"["+d+"]":"";return f.length>1?(e.push(a+g+' ""'),f.forEach(function(a){e.push('"'+c(a)+'"')})):e.push(a+g+' "'+c(b)+'"'),e};this.comments.forEach(function(b){a.push("# "+b)}),this.extractedComments.forEach(function(b){a.push("#. "+b)}),this.references.forEach(function(b){a.push("#: "+b)});var e=Object.keys(this.flags).filter(function(a){return!!this.flags[a]},this);e.length>0&&a.push("#, "+e.join(","));var g=this.obsolete?"#~ ":"";return["msgctxt","msgid","msgid_plural","msgstr"].forEach(function(c){var e=b[c];if(null!=e)if(f(e)&&e.length>1)e.forEach(function(b,e){a=a.concat(g+d(c,b,e))});else{e=f(e)?e.join():e;for(var h=d(c,e),i=1;i<h.length-1;i++)h[i]=h[i].slice(0,-1)+'\\n"';a=a.concat(g+h.join("\n"+g))}}),a.join("\n")},b.exports=g},{fs:3,"lodash.isarray":4}],pofile:[function(a,b,c){b.exports=a("W8CkM0")},{}],3:[function(a,b,c){},{}],4:[function(a,b,c){var d=a("lodash._isnative"),e="[object Array]",f=Object.prototype,g=f.toString,h=d(h=Array.isArray)&&h,i=h||function(a){return a&&"object"==typeof a&&"number"==typeof a.length&&g.call(a)==e||!1};b.exports=i},{"lodash._isnative":5}],5:[function(a,b,c){function d(a){return"function"==typeof a&&g.test(a)}var e=Object.prototype,f=e.toString,g=RegExp("^"+String(f).replace(/[.*+?^${}()|[\]\\]/g,"\\$&").replace(/toString| for [^\]]+/g,".*?")+"$");b.exports=d},{}]},{},["W8CkM0"]);
\ No newline at end of file
diff --git a/lib/po.js b/lib/po.js
index b7a6866..2ab79ba 100644
--- a/lib/po.js
+++ b/lib/po.js
@@ -289,7 +289,9 @@ PO.Item.prototype.toString = function () {
         lines.push('#: ' + ref);
     });
 
-    var flags = Object.keys(this.flags);
+    var flags = Object.keys(this.flags).filter(function (flag) {
+        return !!this.flags[flag];
+    }, this);
     if (flags.length > 0) {
         lines.push('#, ' + flags.join(','));
     }
diff --git a/test/write.js b/test/write.js
index 06edb97..fee578c 100644
--- a/test/write.js
+++ b/test/write.js
@@ -16,6 +16,20 @@ function assertHasLine(str, line) {
     assert(found, 'Could not find line: ' + line);
 }
 
+function assertDoesntHaveLine(str, line) {
+    var lines = str.split('\n');
+    var found = false;
+
+    for (var i = 0; i < lines.length; i++) {
+        if (lines[i].trim() === line) {
+            found = true;
+            break;
+        }
+    }
+
+    assert(!found, 'Shouldn\'t have line: ' + line);
+}
+
 describe('Write', function () {
     it('write flags', function () {
         var input = fs.readFileSync(__dirname + '/fixtures/fuzzy.po', 'utf8');
@@ -24,6 +38,17 @@ describe('Write', function () {
         assertHasLine(str, '#, fuzzy');
     });
 
+    it('write flags only when true', function () {
+        var input = fs.readFileSync(__dirname + '/fixtures/fuzzy.po', 'utf8');
+        var po = PO.parse(input);
+
+        // Flip flag
+        po.items[0].flags.fuzzy = false;
+
+        var str = po.toString();
+        assertDoesntHaveLine(str, '#, fuzzy');
+    });
+
     it('write msgid', function () {
         var input = fs.readFileSync(__dirname + '/fixtures/fuzzy.po', 'utf8');
         var po = PO.parse(input);