diff --git a/README.md b/README.md
index f6f30ea..5074fe7 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,28 @@ In browser:
 var template2 = new UriTemplate("/prefix/{?params*}");
 ```
 
+## Configuration
+You can provide a configuration object as the second argument:
+```javascript
+new UriTemplate("/prefix/{?params*}", {
+	leaveUnmatchedPlaceholders: true
+});
+```
+
+`leaveUnmatchedPlaceholders` defaults to `false`. When `true` any placeholders which do not have a corresponding key in the object, or their value is `null`, will be left in the built URL.
+
+E.g.
+```javascript
+var template = new UriTemplate("/prefix/{a}?arg1={arg1Value}", {
+	leaveUnmatchedPlaceholders: true
+});
+
+console.log(template.fill({
+	a: "something"
+}));
+```
+will output "/prefix/something?arg1={arg1Value}".
+
 ## Substitution using an object
 ```javascript
 // "/categories/green/round/"
diff --git a/test/custom-tests.js b/test/custom-tests.js
index 29316fd..154b1f4 100644
--- a/test/custom-tests.js
+++ b/test/custom-tests.js
@@ -2,41 +2,41 @@ var UriTemplate = require('../uri-templates');
 var assert = require('proclaim');
 
 describe("Guessing variable priority", function () {
-	it('GitHub issue #8', function () {
-		var template = new UriTemplate("{+path}/c/capture{/date,id,page}");
-		var guess = template.fromUri('/a/b/c/capture/20140101/1');
-
-		// we already test elsewhere that this reconstructs correctly - we just want to make sure variables are prioritised left-to-right
-		assert.strictEqual(guess.date, '20140101');
-		assert.strictEqual(guess.id, '1');
-		assert.strictEqual(guess.page, undefined);
-	})
+    it('GitHub issue #8', function () {
+        var template = new UriTemplate("{+path}/c/capture{/date,id,page}");
+        var guess = template.fromUri('/a/b/c/capture/20140101/1');
+
+        // we already test elsewhere that this reconstructs correctly - we just want to make sure variables are prioritised left-to-right
+        assert.strictEqual(guess.date, '20140101');
+        assert.strictEqual(guess.id, '1');
+        assert.strictEqual(guess.page, undefined);
+    })
 });
 
 describe("Original string available", function () {
-	it('GitHub issue #7', function () {
-		var template = new UriTemplate("{+path}/c/capture{/date,id,page}");
+    it('GitHub issue #7', function () {
+        var template = new UriTemplate("{+path}/c/capture{/date,id,page}");
 
-		assert.strictEqual(template.template, '{+path}/c/capture{/date,id,page}');
-		assert.strictEqual(template + "", '{+path}/c/capture{/date,id,page}');
-	})
+        assert.strictEqual(template.template, '{+path}/c/capture{/date,id,page}');
+        assert.strictEqual(template + "", '{+path}/c/capture{/date,id,page}');
+    })
 });
 
 describe("Query optional when decoding", function () {
-	it('GitHub issue #12', function () {
-		var template = new UriTemplate("{/type,ids,field}{?query*}");
+    it('GitHub issue #12', function () {
+        var template = new UriTemplate("{/type,ids,field}{?query*}");
 
-		var uri = '/user/1,2,3/posts';
-		var guess = template.fromUri(uri);
-		assert.isObject(guess);
+        var uri = '/user/1,2,3/posts';
+        var guess = template.fromUri(uri);
+        assert.isObject(guess);
 
-		var trimmed = template.fill(guess).replace(/\?$/, '');
-		assert.strictEqual(trimmed, uri);
-	});
+        var trimmed = template.fill(guess).replace(/\?$/, '');
+        assert.strictEqual(trimmed, uri);
+    });
 });
 
 describe("Decode empty query", function () {
-	it('Must return a empty object', function () {
+    it('Must return a empty object', function () {
         var template = new UriTemplate('{?query}');
 
         var uri = '?';
@@ -45,7 +45,7 @@ describe("Decode empty query", function () {
         assert.isUndefined(guess['']);
     });
 
-	it('Must return a empty object in property', function () {
+    it('Must return a empty object in property', function () {
         var template = new UriTemplate('{?query*}');
 
         var uri = '?';
@@ -54,3 +54,30 @@ describe("Decode empty query", function () {
         assert.isUndefined(guess['']);
     });
 });
+
+describe("'leaveUnmatchedPlaceholders' option enabled", function () {
+    it('Placeholder remains when property missing', function () {
+        var template = new UriTemplate('{a}/{b}{c}', {
+            leaveUnmatchedPlaceholders: true
+        });
+
+        var result = template.fill({
+            a: "1",
+            b: "2"
+        });
+        assert.strictEqual(result, "1/2{c}");
+    });
+
+     it('Placeholder remains when property is null', function () {
+        var template = new UriTemplate('{a}/{b}{c}', {
+            leaveUnmatchedPlaceholders: true
+        });
+
+        var result = template.fill({
+            a: "1",
+            b: "2",
+            c: null
+        });
+        assert.strictEqual(result, "1/2{c}");
+    });
+});
\ No newline at end of file
diff --git a/uri-templates.js b/uri-templates.js
index 96fce41..6f8ec35 100644
--- a/uri-templates.js
+++ b/uri-templates.js
@@ -69,6 +69,7 @@
 		var varSpecMap = {};
 		for (var i = 0; i < varList.length; i++) {
 			var varName = varList[i];
+			var completeVarName = varName;
 			var truncate = null;
 			if (varName.indexOf(":") != -1) {
 				var parts = varName.split(":");
@@ -83,7 +84,8 @@
 			var varSpec = {
 				truncate: truncate,
 				name: varName,
-				suffices: suffices
+				suffices: suffices,
+				completeVarName: completeVarName
 			};
 			varSpecs.push(varSpec);
 			varSpecMap[varName] = varSpec;
@@ -96,6 +98,10 @@
 				var varSpec = varSpecs[i];
 				var value = valueFunction(varSpec.name);
 				if (value == null || (Array.isArray(value) && value.length == 0) || (typeof value == 'object' && Object.keys(value).length == 0)) {
+					if (value == null && this.options.leaveUnmatchedPlaceholders) {
+						// leave this template placeholder in the final url
+						result += "{"+varSpec.completeVarName+"}";
+					}
 					startIndex++;
 					continue;
 				}
@@ -317,7 +323,8 @@
 		};
 	}
 
-	function UriTemplate(template) {
+	function UriTemplate(template, options) {
+		options = options || {};
 		if (!(this instanceof UriTemplate)) {
 			return new UriTemplate(template);
 		}
@@ -349,7 +356,7 @@
 			var result = textParts[0];
 			for (var i = 0; i < substitutions.length; i++) {
 				var substitution = substitutions[i];
-				result += substitution(valueFunction);
+				result += substitution.call(this, valueFunction);
 				result += textParts[i + 1];
 			}
 			return result;
@@ -405,6 +412,7 @@
 		}
 		this.varNames = varNames;
 		this.template = template;
+		this.options = options;
 	}
 	UriTemplate.prototype = {
 		toString: function () {
diff --git a/uri-templates.min.js b/uri-templates.min.js
index 89e7a76..b991afb 100644
--- a/uri-templates.min.js
+++ b/uri-templates.min.js
@@ -1 +1 @@
-!function(a,b){"function"==typeof define&&define.amd?define([],b):"undefined"!=typeof module&&module.exports?module.exports=b():a.UriTemplate=b()}(this,function(){function a(a){return encodeURI(a).replace(/%25[0-9][0-9]/g,function(a){return"%"+a.substring(3)})}function b(b){var c="";d[b.charAt(0)]&&(c=b.charAt(0),b=b.substring(1));var f="",g="",h=!0,i=!1,j=!1;"+"==c?h=!1:"."==c?(g=".",f="."):"/"==c?(g="/",f="/"):"#"==c?(g="#",h=!1):";"==c?(g=";",f=";",i=!0,j=!0):"?"==c?(g="?",f="&",i=!0):"&"==c&&(g="&",f="&",i=!0);for(var k=[],l=b.split(","),m=[],n={},o=0;o<l.length;o++){var p=l[o],q=null;if(-1!=p.indexOf(":")){var r=p.split(":");p=r[0],q=parseInt(r[1])}for(var s={};e[p.charAt(p.length-1)];)s[p.charAt(p.length-1)]=!0,p=p.substring(0,p.length-1);var t={truncate:q,name:p,suffices:s};m.push(t),n[p]=t,k.push(p)}var u=function(b){for(var c="",d=0,e=0;e<m.length;e++){var k=m[e],l=b(k.name);if(null==l||Array.isArray(l)&&0==l.length||"object"==typeof l&&0==Object.keys(l).length)d++;else if(c+=e==d?g:f||",",Array.isArray(l)){i&&(c+=k.name+"=");for(var n=0;n<l.length;n++)n>0&&(c+=k.suffices["*"]?f||",":",",k.suffices["*"]&&i&&(c+=k.name+"=")),c+=h?encodeURIComponent(l[n]).replace(/!/g,"%21"):a(l[n])}else if("object"==typeof l){i&&!k.suffices["*"]&&(c+=k.name+"=");var o=!0;for(var p in l)o||(c+=k.suffices["*"]?f||",":","),o=!1,c+=h?encodeURIComponent(p).replace(/!/g,"%21"):a(p),c+=k.suffices["*"]?"=":",",c+=h?encodeURIComponent(l[p]).replace(/!/g,"%21"):a(l[p])}else i&&(c+=k.name,j&&""==l||(c+="=")),null!=k.truncate&&(l=l.substring(0,k.truncate)),c+=h?encodeURIComponent(l).replace(/!/g,"%21"):a(l)}return c},v=function(a,b){if(g){if(a.substring(0,g.length)!=g)return null;a=a.substring(g.length)}if(1==m.length&&m[0].suffices["*"]){for(var c=m[0],d=c.name,e=c.suffices["*"]?a.split(f||","):[a],j=h&&-1!=a.indexOf("="),k=1;k<e.length;k++){var a=e[k];j&&-1==a.indexOf("=")&&(e[k-1]+=(f||",")+a,e.splice(k,1),k--)}for(var k=0;k<e.length;k++){var a=e[k];h&&-1!=a.indexOf("=")&&(j=!0);for(var l=a.split(","),o=0;o<l.length;o++)h&&(l[o]=decodeURIComponent(l[o]));1==l.length?e[k]=l[0]:e[k]=l}if(i||j){for(var p=b[d]||{},o=0;o<e.length;o++){var q=a;if(!i||q){if("string"==typeof e[o]){var a=e[o],r=a.split("=",1)[0],a=a.substring(r.length+1);q=a}else{var a=e[o][0],r=a.split("=",1)[0],a=a.substring(r.length+1);e[o][0]=a,q=e[o]}void 0!==p[r]?Array.isArray(p[r])?p[r].push(q):p[r]=[p[r],q]:p[r]=q}}1==Object.keys(p).length&&void 0!==p[d]?b[d]=p[d]:b[d]=p}else void 0!==b[d]?Array.isArray(b[d])?b[d]=b[d].concat(e):b[d]=[b[d]].concat(e):1!=e.length||c.suffices["*"]?b[d]=e:b[d]=e[0]}else{for(var e=1==m.length?[a]:a.split(f||","),s={},k=0;k<e.length;k++){for(var t=0;t<m.length-1&&k>t&&!m[t].suffices["*"];t++);if(t!=k){for(var u=m.length-1;u>0&&m.length-u<e.length-k&&!m[u].suffices["*"];u--);m.length-u!=e.length-k?s[k]=t:s[k]=u}else s[k]=k}for(var k=0;k<e.length;k++){var a=e[k];if(a||!i){var l=a.split(","),j=!1;if(i){var a=l[0],d=a.split("=",1)[0],a=a.substring(d.length+1);l[0]=a;var c=n[d]||m[0]}else var c=m[s[k]],d=c.name;for(var o=0;o<l.length;o++)h&&(l[o]=decodeURIComponent(l[o]));(i||c.suffices["*"])&&void 0!==b[d]?Array.isArray(b[d])?b[d]=b[d].concat(l):b[d]=[b[d]].concat(l):1!=l.length||c.suffices["*"]?b[d]=l:b[d]=l[0]}}}};return u.varNames=k,{prefix:g,substitution:u,unSubstitution:v}}function c(a){if(!(this instanceof c))return new c(a);for(var d=a.split("{"),e=[d.shift()],f=[],g=[],h=[],i=[];d.length>0;){var j=d.shift(),k=j.split("}")[0],l=j.substring(k.length+1),m=b(k);g.push(m.substitution),h.push(m.unSubstitution),f.push(m.prefix),e.push(l),i=i.concat(m.substitution.varNames)}this.fill=function(a){if(a&&"function"!=typeof a){var b=a;a=function(a){return b[a]}}for(var c=e[0],d=0;d<g.length;d++){var f=g[d];c+=f(a),c+=e[d+1]}return c},this.fromUri=function(a){for(var b={},c=0;c<e.length;c++){var d=e[c];if(a.substring(0,d.length)!==d)return void 0;if(a=a.substring(d.length),c>=e.length-1){if(""==a)break;return void 0}for(var g=e[c+1],i=c;;){if(i==e.length-2){var j=a.substring(a.length-g.length);if(j!==g)return void 0;var k=a.substring(0,a.length-g.length);a=j}else if(g){var l=a.indexOf(g),k=a.substring(0,l);a=a.substring(l)}else if(f[i+1]){var l=a.indexOf(f[i+1]);-1===l&&(l=a.length);var k=a.substring(0,l);a=a.substring(l)}else{if(e.length>i+2){i++,g=e[i+1];continue}var k=a;a=""}break}h[c](k,b)}return b},this.varNames=i,this.template=a}var d={"+":!0,"#":!0,".":!0,"/":!0,";":!0,"?":!0,"&":!0},e={"*":!0};return c.prototype={toString:function(){return this.template},fillFromObject:function(a){return this.fill(a)}},c});
\ No newline at end of file
+!function(a,b){"function"==typeof define&&define.amd?define([],b):"undefined"!=typeof module&&module.exports?module.exports=b():a.UriTemplate=b()}(this,function(){function a(a){return encodeURI(a).replace(/%25[0-9][0-9]/g,function(a){return"%"+a.substring(3)})}function b(b){var c="";d[b.charAt(0)]&&(c=b.charAt(0),b=b.substring(1));var f="",g="",h=!0,i=!1,j=!1;"+"==c?h=!1:"."==c?(g=".",f="."):"/"==c?(g="/",f="/"):"#"==c?(g="#",h=!1):";"==c?(g=";",f=";",i=!0,j=!0):"?"==c?(g="?",f="&",i=!0):"&"==c&&(g="&",f="&",i=!0);for(var k=[],l=b.split(","),m=[],n={},o=0;o<l.length;o++){var p=l[o],q=p,r=null;if(-1!=p.indexOf(":")){var s=p.split(":");p=s[0],r=parseInt(s[1])}for(var t={};e[p.charAt(p.length-1)];)t[p.charAt(p.length-1)]=!0,p=p.substring(0,p.length-1);var u={truncate:r,name:p,suffices:t,completeVarName:q};m.push(u),n[p]=u,k.push(p)}var v=function(b){for(var c="",d=0,e=0;e<m.length;e++){var k=m[e],l=b(k.name);if(null==l||Array.isArray(l)&&0==l.length||"object"==typeof l&&0==Object.keys(l).length)null==l&&this.options.leaveUnmatchedPlaceholders&&(c+="{"+k.completeVarName+"}"),d++;else if(c+=e==d?g:f||",",Array.isArray(l)){i&&(c+=k.name+"=");for(var n=0;n<l.length;n++)n>0&&(c+=k.suffices["*"]?f||",":",",k.suffices["*"]&&i&&(c+=k.name+"=")),c+=h?encodeURIComponent(l[n]).replace(/!/g,"%21"):a(l[n])}else if("object"==typeof l){i&&!k.suffices["*"]&&(c+=k.name+"=");var o=!0;for(var p in l)o||(c+=k.suffices["*"]?f||",":","),o=!1,c+=h?encodeURIComponent(p).replace(/!/g,"%21"):a(p),c+=k.suffices["*"]?"=":",",c+=h?encodeURIComponent(l[p]).replace(/!/g,"%21"):a(l[p])}else i&&(c+=k.name,j&&""==l||(c+="=")),null!=k.truncate&&(l=l.substring(0,k.truncate)),c+=h?encodeURIComponent(l).replace(/!/g,"%21"):a(l)}return c},w=function(a,b){if(g){if(a.substring(0,g.length)!=g)return null;a=a.substring(g.length)}if(1==m.length&&m[0].suffices["*"]){for(var c=m[0],d=c.name,e=c.suffices["*"]?a.split(f||","):[a],j=h&&-1!=a.indexOf("="),k=1;k<e.length;k++){var a=e[k];j&&-1==a.indexOf("=")&&(e[k-1]+=(f||",")+a,e.splice(k,1),k--)}for(var k=0;k<e.length;k++){var a=e[k];h&&-1!=a.indexOf("=")&&(j=!0);for(var l=a.split(","),o=0;o<l.length;o++)h&&(l[o]=decodeURIComponent(l[o]));1==l.length?e[k]=l[0]:e[k]=l}if(i||j){for(var p=b[d]||{},o=0;o<e.length;o++){var q=a;if(!i||q){if("string"==typeof e[o]){var a=e[o],r=a.split("=",1)[0],a=a.substring(r.length+1);q=a}else{var a=e[o][0],r=a.split("=",1)[0],a=a.substring(r.length+1);e[o][0]=a,q=e[o]}void 0!==p[r]?Array.isArray(p[r])?p[r].push(q):p[r]=[p[r],q]:p[r]=q}}1==Object.keys(p).length&&void 0!==p[d]?b[d]=p[d]:b[d]=p}else void 0!==b[d]?Array.isArray(b[d])?b[d]=b[d].concat(e):b[d]=[b[d]].concat(e):1!=e.length||c.suffices["*"]?b[d]=e:b[d]=e[0]}else{for(var e=1==m.length?[a]:a.split(f||","),s={},k=0;k<e.length;k++){for(var t=0;t<m.length-1&&k>t&&!m[t].suffices["*"];t++);if(t!=k){for(var u=m.length-1;u>0&&m.length-u<e.length-k&&!m[u].suffices["*"];u--);m.length-u!=e.length-k?s[k]=t:s[k]=u}else s[k]=k}for(var k=0;k<e.length;k++){var a=e[k];if(a||!i){var l=a.split(","),j=!1;if(i){var a=l[0],d=a.split("=",1)[0],a=a.substring(d.length+1);l[0]=a;var c=n[d]||m[0]}else var c=m[s[k]],d=c.name;for(var o=0;o<l.length;o++)h&&(l[o]=decodeURIComponent(l[o]));(i||c.suffices["*"])&&void 0!==b[d]?Array.isArray(b[d])?b[d]=b[d].concat(l):b[d]=[b[d]].concat(l):1!=l.length||c.suffices["*"]?b[d]=l:b[d]=l[0]}}}};return v.varNames=k,{prefix:g,substitution:v,unSubstitution:w}}function c(a,d){if(d=d||{},!(this instanceof c))return new c(a);for(var e=a.split("{"),f=[e.shift()],g=[],h=[],i=[],j=[];e.length>0;){var k=e.shift(),l=k.split("}")[0],m=k.substring(l.length+1),n=b(l);h.push(n.substitution),i.push(n.unSubstitution),g.push(n.prefix),f.push(m),j=j.concat(n.substitution.varNames)}this.fill=function(a){if(a&&"function"!=typeof a){var b=a;a=function(a){return b[a]}}for(var c=f[0],d=0;d<h.length;d++){var e=h[d];c+=e.call(this,a),c+=f[d+1]}return c},this.fromUri=function(a){for(var b={},c=0;c<f.length;c++){var d=f[c];if(a.substring(0,d.length)!==d)return void 0;if(a=a.substring(d.length),c>=f.length-1){if(""==a)break;return void 0}for(var e=f[c+1],h=c;;){if(h==f.length-2){var j=a.substring(a.length-e.length);if(j!==e)return void 0;var k=a.substring(0,a.length-e.length);a=j}else if(e){var l=a.indexOf(e),k=a.substring(0,l);a=a.substring(l)}else if(g[h+1]){var l=a.indexOf(g[h+1]);-1===l&&(l=a.length);var k=a.substring(0,l);a=a.substring(l)}else{if(f.length>h+2){h++,e=f[h+1];continue}var k=a;a=""}break}i[c](k,b)}return b},this.varNames=j,this.template=a,this.options=d}var d={"+":!0,"#":!0,".":!0,"/":!0,";":!0,"?":!0,"&":!0},e={"*":!0};return c.prototype={toString:function(){return this.template},fillFromObject:function(a){return this.fill(a)}},c});
\ No newline at end of file