diff --git a/lib/_007/Test.pm b/lib/_007/Test.pm
index 90e4d6a4..9ab95dba 100644
--- a/lib/_007/Test.pm
+++ b/lib/_007/Test.pm
@@ -272,7 +272,7 @@ sub is-result($input, $expected, $desc = "MISSING TEST DESCRIPTION") is export {
     is $output.result, $expected, $desc;
 }
 
-sub is-error($input, $expected-error, $desc = $expected-error.^name) is export {
+sub is-error($input, $expected-error, $expected-msg, $desc = $expected-error.^name) is export {
     my $ast = read($input);
     my $output = StrOutput.new;
     my $runtime = _007.runtime(:$output);
@@ -281,7 +281,7 @@ sub is-error($input, $expected-error, $desc = $expected-error.^name) is export {
 
     CATCH {
         when $expected-error {
-            pass $desc;
+            is .message, $expected-msg, $desc;
         }
     }
     flunk $desc;
diff --git a/t/features/builtins/methods.t b/t/features/builtins/methods.t
index 05ebb657..a5cf5a8d 100644
--- a/t/features/builtins/methods.t
+++ b/t/features/builtins/methods.t
@@ -189,7 +189,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:() (postfix:. (str "abc") (identifier "charat")) (argumentlist (int 3)))))))
         .
 
-    is-error $ast, X::Subscript::TooLarge, "charat() dies";
+    is-error
+        $ast,
+        X::Subscript::TooLarge,
+        "Subscript (3) too large (array length 3)",
+        "charat() dies";
 }
 
 {
@@ -271,7 +275,11 @@ use _007::Test;
           (stexpr (postfix:() (postfix:. (identifier "a") (identifier "pop")) (argumentlist))))
         .
 
-    is-error $ast, X::Cannot::Empty, "cannot Array.pop() an empty array";
+    is-error
+        $ast,
+        X::Cannot::Empty,
+        "Cannot pop from an empty Val::Array",
+        "cannot Array.pop() an empty array";
 }
 
 {
@@ -304,7 +312,11 @@ use _007::Test;
           (stexpr (postfix:() (postfix:. (identifier "a") (identifier "shift")) (argumentlist))))
         .
 
-    is-error $ast, X::Cannot::Empty, "cannot Array.shift() an empty array";
+    is-error
+        $ast,
+        X::Cannot::Empty,
+        "Cannot pop from an empty Val::Array",
+        "cannot Array.shift() an empty array";
 }
 
 {
@@ -347,7 +359,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:() (postfix:. (identifier "r") (identifier "fullmatch")) (argumentlist (int 3)))))))
         .
 
-    is-error $ast, X::Regex::InvalidMatchType, "Regex.fullmatch() can only match strings";
+    is-error
+        $ast,
+        X::Regex::InvalidMatchType,
+        "A regex can only match strings",
+        "Regex.fullmatch() can only match strings";
 }
 
 {
@@ -357,7 +373,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:() (postfix:. (identifier "r") (identifier "search")) (argumentlist (int 3)))))))
         .
 
-    is-error $ast, X::Regex::InvalidMatchType, "Regex.search() can only match strings";
+    is-error
+        $ast,
+        X::Regex::InvalidMatchType,
+        "A regex can only match strings",
+        "Regex.search() can only match strings";
 }
 
 {
diff --git a/t/features/builtins/operators.t b/t/features/builtins/operators.t
index 037f149b..20705f9c 100644
--- a/t/features/builtins/operators.t
+++ b/t/features/builtins/operators.t
@@ -53,7 +53,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (infix:% (int 5) (int 0))))))
         .
 
-    is-error $ast, X::Numeric::DivideByZero, "dividing by 0 is an error";
+    is-error
+        $ast,
+        X::Numeric::DivideByZero,
+        "Attempt to divide 5 by zero using %",
+        "dividing by 0 is an error";
 }
 
 {
@@ -74,7 +78,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (infix:%% (int 5) (int 0))))))
         .
 
-    is-error $ast, X::Numeric::DivideByZero, "checking divisibility by 0 is an error";
+    is-error
+        $ast,
+        X::Numeric::DivideByZero,
+        "Attempt to divide 5 by zero using %%",
+        "checking divisibility by 0 is an error";
 }
 
 {
@@ -410,7 +418,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:[] (identifier "ns") (prefix:- (int 2)))))))
         .
 
-    is-error $ast, X::Subscript::Negative, "negative array indexing is an error";
+    is-error
+        $ast,
+        X::Subscript::Negative,
+        "Calculated index (-2) is negative, but Array allows only 0-based indexing",
+        "negative array indexing is an error";
 }
 
 {
@@ -420,7 +432,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:[] (identifier "ns") (int 19))))))
         .
 
-    is-error $ast, X::Subscript::TooLarge, "indexing beyond the last element is an error";
+    is-error
+        $ast,
+        X::Subscript::TooLarge,
+        "Subscript (19) too large (array length 2)",
+        "indexing beyond the last element is an error";
 }
 
 {
@@ -429,7 +445,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (infix:+ (int 38) (str "4"))))))
         .
 
-    is-error $ast, X::TypeCheck, "adding non-ints is an error";
+    is-error
+        $ast,
+        X::TypeCheck,
+        "Type check failed in +; expected Val::Int but got Val::Str (Val::Str.new(value =>...)",
+        "adding non-ints is an error";
 }
 
 {
@@ -438,7 +458,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (infix:~ (int 38) (str "4"))))))
         .
 
-    is-error $ast, X::TypeCheck, "concatenating non-strs is an error";
+    is-error
+        $ast,
+        X::TypeCheck,
+        "Type check failed in ~; expected Val::Str but got Val::Int (Val::Int.new(value =>...)",
+        "concatenating non-strs is an error";
 }
 
 {
@@ -448,7 +472,11 @@ use _007::Test;
           (stexpr (postfix:() (identifier "say") (argumentlist (postfix:[] (identifier "ns") (int 0))))))
         .
 
-    is-error $ast, X::TypeCheck, "indexing a non-array is an error";
+    is-error
+        $ast,
+        X::TypeCheck,
+        "Type check failed in indexing; expected Val::Array but got Val::Str (Val::Str.new(value =>...)",
+        "indexing a non-array is an error";
 }
 
 {
@@ -593,7 +621,11 @@ use _007::Test;
           (stexpr (prefix:^ (str "Mr Bond"))))
         .
 
-    is-error $ast, X::TypeCheck, "can't upto a string (or other non-integer types)";
+    is-error
+        $ast,
+        X::TypeCheck,
+        "Type check failed in ^; expected Val::Int but got Val::Str (Val::Str.new(value =>...)",
+        "can't upto a string (or other non-integer types)";
 }
 
 {
diff --git a/t/features/for-loop.t b/t/features/for-loop.t
index 57117fbf..e6d5c15e 100644
--- a/t/features/for-loop.t
+++ b/t/features/for-loop.t
@@ -30,7 +30,11 @@ use _007::Test;
             (stexpr (postfix:() (identifier "say") (argumentlist (identifier "j"))))))))
         .
 
-    is-error $ast, X::ParameterMismatch, "for-loops with more parameters are not supported";
+    is-error
+        $ast,
+        X::ParameterMismatch,
+        "For loop with 2 parameters called with 0 or 1 arguments",
+        "for-loops with more parameters are not supported";
 }
 
 {
diff --git a/t/features/objects.t b/t/features/objects.t
index 22cda14c..0f634a4b 100644
--- a/t/features/objects.t
+++ b/t/features/objects.t
@@ -58,7 +58,11 @@ use _007::Test;
             (stexpr (postfix:. (identifier "o") (identifier "a"))))
         .
 
-    is-error $ast, X::Property::NotFound, "can't access non-existing property (dot syntax)";
+    is-error
+        $ast,
+        X::Property::NotFound,
+        "Property 'a' not found on object of type Object",
+        "can't access non-existing property (dot syntax)";
 }
 
 {
@@ -67,7 +71,11 @@ use _007::Test;
            (stexpr (postfix:. (int 42) (identifier "a"))))
         .
 
-    is-error $ast, X::Property::NotFound, "can't access property on Val::Int (dot syntax)";
+    is-error
+        $ast,
+        X::Property::NotFound,
+        "Property 'a' not found on object of type Int",
+        "can't access property on Val::Int (dot syntax)";
 }
 
 {
@@ -81,6 +89,7 @@ use _007::Test;
     is-error
         $ast,
         X::Property::Duplicate,
+        "The property 'foo' was declared more than once in a property list",
         "can't have duplicate properties (#85) (I)";
 }
 
@@ -102,7 +111,11 @@ use _007::Test;
             (stexpr (postfix:[] (identifier "o") (str "b"))))
         .
 
-    is-error $ast, X::Property::NotFound, "can't access non-existing property (brackets syntax)";
+    is-error
+        $ast,
+        X::Property::NotFound,
+        "Property 'b' not found on object of type Object",
+        "can't access non-existing property (brackets syntax)";
 }
 
 {
diff --git a/t/features/types.t b/t/features/types.t
index 6f0a7dc0..60c8f27f 100644
--- a/t/features/types.t
+++ b/t/features/types.t
@@ -67,7 +67,11 @@ use _007::Test;
           (stexpr (object (identifier "Q::Literal") (propertylist))))
         .
 
-    is-error $ast, X::Uninstantiable, "abstract Q types are uninstantiable (#140)";
+    is-error
+        $ast,
+        X::Uninstantiable,
+        "<type Q::Literal> is abstract and uninstantiable",
+        "abstract Q types are uninstantiable (#140)";
 }
 
 {
diff --git a/t/features/while-loop.t b/t/features/while-loop.t
index f19a1080..78a39fe3 100644
--- a/t/features/while-loop.t
+++ b/t/features/while-loop.t
@@ -62,7 +62,11 @@ use _007::Test;
             (stexpr (infix:= (identifier "u") (infix:+ (identifier "u") (prefix:- (int 1)))))))))
         .
 
-    is-error $ast, X::ParameterMismatch, "while loops don't accept more than one parameter";
+    is-error
+        $ast,
+        X::ParameterMismatch,
+        "While loop with 3 parameters called with 0 or 1 arguments",
+        "while loops don't accept more than one parameter";
 }
 
 done-testing;