diff --git a/kiss/src/kiss/Macros.hx b/kiss/src/kiss/Macros.hx
index e1e3cf7e..dde08093 100644
--- a/kiss/src/kiss/Macros.hx
+++ b/kiss/src/kiss/Macros.hx
@@ -309,11 +309,11 @@ class Macros {
             wholeExp.checkNumArgs(1, 2, "(assert [expression] [message])");
             var b = wholeExp.expBuilder();
             var expression = exps[0];
-            var basicMessage = 'Assertion ${expression.def.toString()} failed';
+            var failureError = KissError.fromExp(wholeExp, "").toString(AssertionFail);
             var messageExp = if (exps.length > 1) {
-                b.callSymbol("+", [b.str(basicMessage + ": "), exps[1]]);
+                exps[1];
             } else {
-                b.str(basicMessage);
+                b.str("");
             };
             var letVal = b.symbol();
             b.callSymbol("let", [
@@ -324,7 +324,9 @@ class Macros {
                 b.callSymbol("if", [
                     letVal,
                     letVal,
-                    b.callSymbol("throw", [messageExp])
+                    b.callSymbol("throw", [
+                        b.callSymbol("kiss.Prelude.runtimeInsertAssertionMessage", [messageExp, b.str(failureError)])
+                    ])
                 ])
             ]);
         };
diff --git a/kiss/src/kiss/Prelude.hx b/kiss/src/kiss/Prelude.hx
index 43da7900..7ccdc4ae 100644
--- a/kiss/src/kiss/Prelude.hx
+++ b/kiss/src/kiss/Prelude.hx
@@ -691,6 +691,15 @@ class Prelude {
         return str.substr(negIdx(startIdx), negIdx(endIdx));
     }
 
+    public static function runtimeInsertAssertionMessage(message:String, error:String) {
+        var colonIdx = 0;
+        for (_ in 0...4) {
+            colonIdx = error.indexOf(":", colonIdx) + 1;
+        }
+        colonIdx += 1;
+        return error.substr(0, colonIdx) + message + error.substr(colonIdx);
+    }
+
     public static var newLine = "\n";
     public static var backSlash = "\\";
     public static var doubleQuote = "\"";
diff --git a/kiss/src/test/cases/BasicTestCase.kiss b/kiss/src/test/cases/BasicTestCase.kiss
index cbfb3d4a..b7c8c785 100644
--- a/kiss/src/test/cases/BasicTestCase.kiss
+++ b/kiss/src/test/cases/BasicTestCase.kiss
@@ -327,7 +327,8 @@
     (try
             (assert false (+ "false " "should " "have " "been " "true"))
         (catch [:String message]
-            (Assert.equals "Assertion false failed: false should have been true" message)))
+            (Assert.equals "kiss/src/test/cases/BasicTestCase.kiss:328:13: Assertion failed: false should have been true
+From:[(assert false (+ \"false \" \"should \" \"have \" \"been \" \"true\"))]" message)))
     
     (assert true)
     (assert ![]))