diff --git a/src/htmx.js b/src/htmx.js
index 26cc929e6..d0bbffa9a 100644
--- a/src/htmx.js
+++ b/src/htmx.js
@@ -1929,18 +1929,22 @@ return (function () {
         function addHxOnEventHandler(elt, eventName, code) {
             var nodeData = getInternalData(elt);
             nodeData.onHandlers = [];
-            var func = new Function("event", code + "; return;");
+            var func;
             var listener = function (e) {
-                return func.call(elt, e);
+                return maybeEval(elt, function() {
+                    if (!func) {
+                        func = new Function("event", code);
+                    }
+                    func.call(elt, e);
+                });
             };
             elt.addEventListener(eventName, listener);
             nodeData.onHandlers.push({event:eventName, listener:listener});
-            return {nodeData:nodeData, code:code, func:func, listener:listener};
         }
 
         function processHxOn(elt) {
             var hxOnValue = getAttributeValue(elt, 'hx-on');
-            if (hxOnValue && htmx.config.allowEval) {
+            if (hxOnValue) {
                 var handlers = {}
                 var lines = hxOnValue.split("\n");
                 var currentEvent = null;
diff --git a/test/attributes/hx-on-wildcard.js b/test/attributes/hx-on-wildcard.js
index 920214727..1bde519af 100644
--- a/test/attributes/hx-on-wildcard.js
+++ b/test/attributes/hx-on-wildcard.js
@@ -130,4 +130,21 @@ describe("hx-on:* attribute", function() {
         delete window.tempCount;
     });
 
+    it("is not evaluated when allowEval is false", function () {
+        var calledEvent = false;
+        var handler = htmx.on("htmx:evalDisallowedError", function(){
+            calledEvent = true;
+        });
+        htmx.config.allowEval = false;
+        try {
+            var btn = make("<button hx-on:click='window.foo = true'>Foo</button>");
+            btn.click();
+            should.not.exist(window.foo);
+        } finally {
+            htmx.config.allowEval = true;
+            htmx.off("htmx:evalDisallowedError", handler);
+            delete window.foo;
+        }
+        calledEvent.should.equal(true);
+    });
 });
diff --git a/test/attributes/hx-on.js b/test/attributes/hx-on.js
index 9a2005b11..5bb5ac22d 100644
--- a/test/attributes/hx-on.js
+++ b/test/attributes/hx-on.js
@@ -119,4 +119,21 @@ describe("hx-on attribute", function() {
         delete window.tempCount;
     });
 
+    it("is not evaluated when allowEval is false", function () {
+        var calledEvent = false;
+        var handler = htmx.on("htmx:evalDisallowedError", function(){
+            calledEvent = true;
+        });
+        htmx.config.allowEval = false;
+        try {
+            var btn = make("<button hx-on='click: window.foo = true'>Foo</button>");
+            btn.click();
+            should.not.exist(window.foo);
+        } finally {
+            htmx.config.allowEval = true;
+            htmx.off("htmx:evalDisallowedError", handler);
+            delete window.foo;
+        }
+        calledEvent.should.equal(true);
+    });
 });
diff --git a/test/attributes/hx-vals.js b/test/attributes/hx-vals.js
index e2728e2c4..4c7e2d335 100644
--- a/test/attributes/hx-vals.js
+++ b/test/attributes/hx-vals.js
@@ -252,4 +252,49 @@ describe("hx-vals attribute", function() {
         div.innerHTML.should.equal("Clicked!");
     });
 
+    it('javascript: is not evaluated when allowEval is false', function () {
+        var calledEvent = false;
+        var handler = htmx.on("htmx:evalDisallowedError", function(){
+            calledEvent = true;
+        });
+        try {
+            htmx.config.allowEval = false;
+            this.server.respondWith("POST", "/vars", function (xhr) {
+                var params = getParameters(xhr);
+                should.not.exist(params['i1']);
+                xhr.respond(200, {}, "Clicked!")
+            });
+            var div = make('<div hx-post="/vars" hx-vals="javascript:i1:\'test\'"></div>')
+            div.click();
+            this.server.respond();
+            div.innerHTML.should.equal("Clicked!");
+        } finally {
+            htmx.config.allowEval = true;
+            htmx.off("htmx:evalDisallowedError", handler);
+        }
+        calledEvent.should.equal(true);
+    });
+
+    it('js: is not evaluated when allowEval is false', function () {
+        var calledEvent = false;
+        var handler = htmx.on("htmx:evalDisallowedError", function(){
+            calledEvent = true;
+        });
+        try {
+            htmx.config.allowEval = false;
+            this.server.respondWith("POST", "/vars", function (xhr) {
+                var params = getParameters(xhr);
+                should.not.exist(params['i1']);
+                xhr.respond(200, {}, "Clicked!")
+            });
+            var div = make('<div hx-post="/vars" hx-vals="js:i1:\'test\'"></div>')
+            div.click();
+            this.server.respond();
+            div.innerHTML.should.equal("Clicked!");
+        } finally {
+            htmx.config.allowEval = true;
+            htmx.off("htmx:evalDisallowedError", handler);
+        }
+        calledEvent.should.equal(true);
+    });
 });
diff --git a/test/attributes/hx-vars.js b/test/attributes/hx-vars.js
index be20caf43..f9647c0a5 100644
--- a/test/attributes/hx-vars.js
+++ b/test/attributes/hx-vars.js
@@ -152,4 +152,26 @@ describe("hx-vars attribute", function() {
         div.innerHTML.should.equal("Clicked!");
     });
 
+    it('is not evaluated when allowEval is false', function () {
+        var calledEvent = false;
+        var handler = htmx.on("htmx:evalDisallowedError", function(){
+            calledEvent = true;
+        });
+        try {
+            htmx.config.allowEval = false;
+            this.server.respondWith("POST", "/vars", function (xhr) {
+                var params = getParameters(xhr);
+                should.not.exist(params['i1']);
+                xhr.respond(200, {}, "Clicked!")
+            });
+            var div = make('<div hx-post="/vars" hx-vals="javascript:i1:\'test\'"></div>')
+            div.click();
+            this.server.respond();
+            div.innerHTML.should.equal("Clicked!");
+        } finally {
+            htmx.config.allowEval = true;
+            htmx.off("htmx:evalDisallowedError", handler);
+        }
+        calledEvent.should.equal(true);
+    });
 });