diff --git a/src/eval/args.rs b/src/eval/args.rs
index aadd7d549..8617bd93a 100644
--- a/src/eval/args.rs
+++ b/src/eval/args.rs
@@ -158,7 +158,13 @@ impl Args {
     /// argument.
     pub fn finish(self) -> SourceResult<()> {
         if let Some(arg) = self.items.first() {
-            bail!(arg.span, "unexpected argument");
+            bail!(
+                arg.span,
+                match &arg.name {
+                    Some(name) => eco_format!("unexpected argument: {}", name),
+                    _ => eco_format!("unexpected argument"),
+                }
+            )
         }
         Ok(())
     }
diff --git a/src/eval/scope.rs b/src/eval/scope.rs
index e241cac59..f2207188a 100644
--- a/src/eval/scope.rs
+++ b/src/eval/scope.rs
@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 use std::fmt::{self, Debug, Formatter};
 use std::hash::Hash;
 
-use ecow::EcoString;
+use ecow::{eco_format, EcoString};
 
 use super::{Library, Value};
 use crate::diag::StrResult;
@@ -42,7 +42,7 @@ impl<'a> Scopes<'a> {
             .chain(self.scopes.iter().rev())
             .chain(self.base.map(|base| base.global.scope()))
             .find_map(|scope| scope.get(var))
-            .ok_or("unknown variable")?)
+            .ok_or(eco_format!("unknown variable: {}", var))?)
     }
 
     /// Try to access a variable immutably in math.
@@ -51,7 +51,7 @@ impl<'a> Scopes<'a> {
             .chain(self.scopes.iter().rev())
             .chain(self.base.map(|base| base.math.scope()))
             .find_map(|scope| scope.get(var))
-            .ok_or("unknown variable")?)
+            .ok_or(eco_format!("unknown variable: {}", var))?)
     }
 
     /// Try to access a variable mutably.
@@ -61,8 +61,8 @@ impl<'a> Scopes<'a> {
             .find_map(|scope| scope.get_mut(var))
             .ok_or_else(|| {
                 match self.base.and_then(|base| base.global.scope().get(var)) {
-                    Some(_) => "cannot mutate a constant",
-                    _ => "unknown variable",
+                    Some(_) => eco_format!("cannot mutate a constant: {}", var),
+                    _ => eco_format!("unknown variable: {}", var),
                 }
             })?
     }
diff --git a/src/syntax/lexer.rs b/src/syntax/lexer.rs
index 7961d4cac..dcd2509af 100644
--- a/src/syntax/lexer.rs
+++ b/src/syntax/lexer.rs
@@ -217,7 +217,7 @@ impl Lexer<'_> {
                 .and_then(std::char::from_u32)
                 .is_none()
             {
-                return self.error("invalid unicode escape sequence");
+                return self.error(eco_format!("invalid unicode codepoint: {}", hex));
             }
 
             return SyntaxKind::Escape;
@@ -585,10 +585,10 @@ impl Lexer<'_> {
             SyntaxKind::Float
         } else {
             return self.error(match base {
-                2 => "invalid binary number",
-                8 => "invalid octal number",
-                16 => "invalid hexadecimal number",
-                _ => "invalid number",
+                2 => eco_format!("invalid binary number: 0b{}", number),
+                8 => eco_format!("invalid octal number: 0o{}", number),
+                16 => eco_format!("invalid hexadecimal number: 0x{}", number),
+                _ => eco_format!("invalid number: {}", number),
             });
         };
 
@@ -600,7 +600,7 @@ impl Lexer<'_> {
             suffix,
             "pt" | "mm" | "cm" | "in" | "deg" | "rad" | "em" | "fr" | "%"
         ) {
-            return self.error("invalid number suffix");
+            return self.error(eco_format!("invalid number suffix: {}", suffix));
         }
 
         SyntaxKind::Numeric
diff --git a/src/syntax/parser.rs b/src/syntax/parser.rs
index e68074045..4bc25a30d 100644
--- a/src/syntax/parser.rs
+++ b/src/syntax/parser.rs
@@ -1046,8 +1046,8 @@ fn validate_dict(p: &mut Parser, m: Marker) {
                     None => first.text().clone(),
                 };
 
-                if !used.insert(key) {
-                    first.convert_to_error("duplicate key");
+                if !used.insert(key.clone()) {
+                    first.convert_to_error(eco_format!("duplicate key: {}", key));
                     child.make_erroneous();
                 }
             }
@@ -1073,13 +1073,19 @@ fn validate_params(p: &mut Parser, m: Marker) {
         match child.kind() {
             SyntaxKind::Ident => {
                 if !used.insert(child.text().clone()) {
-                    child.convert_to_error("duplicate parameter");
+                    child.convert_to_error(eco_format!(
+                        "duplicate parameter: {}",
+                        child.text()
+                    ));
                 }
             }
             SyntaxKind::Named => {
                 let Some(within) = child.children_mut().first_mut() else { return };
                 if !used.insert(within.text().clone()) {
-                    within.convert_to_error("duplicate parameter");
+                    within.convert_to_error(eco_format!(
+                        "duplicate parameter: {}",
+                        within.text()
+                    ));
                     child.make_erroneous();
                 }
             }
@@ -1101,7 +1107,10 @@ fn validate_params(p: &mut Parser, m: Marker) {
                     continue;
                 }
                 if !used.insert(within.text().clone()) {
-                    within.convert_to_error("duplicate parameter");
+                    within.convert_to_error(eco_format!(
+                        "duplicate parameter: {}",
+                        within.text()
+                    ));
                     child.make_erroneous();
                 }
             }
@@ -1122,7 +1131,10 @@ fn validate_args(p: &mut Parser, m: Marker) {
         if child.kind() == SyntaxKind::Named {
             let Some(within) = child.children_mut().first_mut() else { return };
             if !used.insert(within.text().clone()) {
-                within.convert_to_error("duplicate argument");
+                within.convert_to_error(eco_format!(
+                    "duplicate argument: {}",
+                    within.text()
+                ));
                 child.make_erroneous();
             }
         }
diff --git a/tests/typ/compiler/array.typ b/tests/typ/compiler/array.typ
index 97b5da521..c9e85ed77 100644
--- a/tests/typ/compiler/array.typ
+++ b/tests/typ/compiler/array.typ
@@ -224,7 +224,7 @@
 // Error: 4-6 unexpected end of block comment
 #(1*/2)
 
-// Error: 6-8 invalid number suffix
+// Error: 6-8 invalid number suffix: u
 #(1, 1u 2)
 
 // Error: 3-4 unexpected comma
diff --git a/tests/typ/compiler/block.typ b/tests/typ/compiler/block.typ
index bb23c0fe7..81c719da5 100644
--- a/tests/typ/compiler/block.typ
+++ b/tests/typ/compiler/block.typ
@@ -61,7 +61,7 @@
 // Block directly in markup also creates a scope.
 #{ let x = 1 }
 
-// Error: 7-8 unknown variable
+// Error: 7-8 unknown variable: x
 #test(x, 1)
 
 ---
@@ -73,7 +73,7 @@
 
 #test(a, 1)
 
-// Error: 3-4 unknown variable
+// Error: 3-4 unknown variable: b
 #{b}
 
 ---
@@ -83,7 +83,7 @@
   test(b, 1)
 }}
 
-// Error: 2-3 unknown variable
+// Error: 2-3 unknown variable: b
 #b
 
 ---
@@ -106,13 +106,13 @@
 // Content blocks also create a scope.
 #[#let x = 1]
 
-// Error: 2-3 unknown variable
+// Error: 2-3 unknown variable: x
 #x
 
 ---
 // Multiple unseparated expressions in one line.
 
-// Error: 2-4 invalid number suffix
+// Error: 2-4 invalid number suffix: u
 #1u
 
 // Should output `1`.
diff --git a/tests/typ/compiler/call.typ b/tests/typ/compiler/call.typ
index f78dec20b..04eb29064 100644
--- a/tests/typ/compiler/call.typ
+++ b/tests/typ/compiler/call.typ
@@ -44,7 +44,7 @@
 }
 
 ---
-// Error: 26-30 duplicate argument
+// Error: 26-30 duplicate argument: font
 #set text(font: "Arial", font: "Helvetica")
 
 ---
diff --git a/tests/typ/compiler/closure.typ b/tests/typ/compiler/closure.typ
index a1e51d56c..915de8509 100644
--- a/tests/typ/compiler/closure.typ
+++ b/tests/typ/compiler/closure.typ
@@ -106,7 +106,7 @@
 ---
 // Don't leak environment.
 #{
-  // Error: 16-17 unknown variable
+  // Error: 16-17 unknown variable: x
   let func() = x
   let x = "hi"
   func()
@@ -141,22 +141,22 @@
   test(greet("Typst"), "Hey, Typst!")
   test(greet("Typst", birthday: true), "Happy Birthday, Typst!")
 
-  // Error: 23-35 unexpected argument
+  // Error: 23-35 unexpected argument: whatever
   test(greet("Typst", whatever: 10))
 }
 
 ---
-// Error: 11-12 duplicate parameter
+// Error: 11-12 duplicate parameter: x
 #let f(x, x) = none
 
 ---
-// Error: 14-15 duplicate parameter
-// Error: 23-24 duplicate parameter
-// Error: 35-36 duplicate parameter
+// Error: 14-15 duplicate parameter: a
+// Error: 23-24 duplicate parameter: b
+// Error: 35-36 duplicate parameter: b
 #let f(a, b, a: none, b: none, c, b) = none
 
 ---
-// Error: 13-14 duplicate parameter
+// Error: 13-14 duplicate parameter: a
 #let f(a, ..a) = none
 
 ---
diff --git a/tests/typ/compiler/dict.typ b/tests/typ/compiler/dict.typ
index fb0a59a36..6c982ed44 100644
--- a/tests/typ/compiler/dict.typ
+++ b/tests/typ/compiler/dict.typ
@@ -56,11 +56,11 @@
 #test(dict, (a: 3, b: 1))
 
 ---
-// Error: 24-29 duplicate key
+// Error: 24-29 duplicate key: first
 #(first: 1, second: 2, first: 3)
 
 ---
-// Error: 17-20 duplicate key
+// Error: 17-20 duplicate key: a
 #(a: 1, "b": 2, "a": 3)
 
 ---
diff --git a/tests/typ/compiler/include.typ b/tests/typ/compiler/include.typ
index fa2e84c04..586e869bb 100644
--- a/tests/typ/compiler/include.typ
+++ b/tests/typ/compiler/include.typ
@@ -24,7 +24,7 @@
 #include "modules/chap1.typ"
 
 // The variables of the file should not appear in this scope.
-// Error: 2-6 unknown variable
+// Error: 2-6 unknown variable: name
 #name
 
 ---
diff --git a/tests/typ/compiler/methods.typ b/tests/typ/compiler/methods.typ
index 86faefbcb..afcb024fd 100644
--- a/tests/typ/compiler/methods.typ
+++ b/tests/typ/compiler/methods.typ
@@ -42,5 +42,5 @@
 #(numbers.sorted() = 1)
 
 ---
-// Error: 2-5 cannot mutate a constant
+// Error: 2-5 cannot mutate a constant: box
 #box.push(1)
diff --git a/tests/typ/compiler/ops-invalid.typ b/tests/typ/compiler/ops-invalid.typ
index 8ccbb8b77..3ab629296 100644
--- a/tests/typ/compiler/ops-invalid.typ
+++ b/tests/typ/compiler/ops-invalid.typ
@@ -97,7 +97,7 @@
 }
 
 ---
-// Error: 4-5 unknown variable
+// Error: 4-5 unknown variable: x
 #((x) = "")
 
 ---
@@ -110,15 +110,15 @@
 #(not x = "a")
 
 ---
-// Error: 7-8 unknown variable
+// Error: 7-8 unknown variable: x
 #(1 + x += 3)
 
 ---
-// Error: 3-4 unknown variable
+// Error: 3-4 unknown variable: z
 #(z = 1)
 
 ---
-// Error: 3-7 cannot mutate a constant
+// Error: 3-7 cannot mutate a constant: rect
 #(rect = "hi")
 
 ---
diff --git a/tests/typ/compiler/ops.typ b/tests/typ/compiler/ops.typ
index 1a9a2169b..a6c64cbd6 100644
--- a/tests/typ/compiler/ops.typ
+++ b/tests/typ/compiler/ops.typ
@@ -116,11 +116,11 @@
 #test(0xA + 0xa, 0x14)
 
 ---
-// Error: 2-7 invalid binary number
+// Error: 2-7 invalid binary number: 0b123
 #0b123
 
 ---
-// Error: 2-8 invalid hexadecimal number
+// Error: 2-8 invalid hexadecimal number: 0x123z
 #0x123z
 
 ---
@@ -201,7 +201,7 @@
 #(x += "thing") #test(x, "something")
 
 ---
-// Error: 3-6 cannot mutate a constant
+// Error: 3-6 cannot mutate a constant: box
 #(box = 1)
 
 ---
diff --git a/tests/typ/compiler/recursion.typ b/tests/typ/compiler/recursion.typ
index ae214631a..1bd53178f 100644
--- a/tests/typ/compiler/recursion.typ
+++ b/tests/typ/compiler/recursion.typ
@@ -15,7 +15,7 @@
 
 ---
 // Test with unnamed function.
-// Error: 17-18 unknown variable
+// Error: 17-18 unknown variable: f
 #let f = (n) => f(n - 1)
 #f(10)
 
diff --git a/tests/typ/text/escape.typ b/tests/typ/text/escape.typ
index 95a8a027a..e7ec9023e 100644
--- a/tests/typ/text/escape.typ
+++ b/tests/typ/text/escape.typ
@@ -27,7 +27,7 @@ let f() , ; : | + - /= == 12 "string"
 
 ---
 // Unicode codepoint does not exist.
-// Error: 1-11 invalid unicode escape sequence
+// Error: 1-11 invalid unicode codepoint: FFFFFF
 \u{FFFFFF}
 
 ---
diff --git a/tests/typ/text/font.typ b/tests/typ/text/font.typ
index 9844d066e..07d00d143 100644
--- a/tests/typ/text/font.typ
+++ b/tests/typ/text/font.typ
@@ -56,5 +56,5 @@ Emoji: 🐪, 🌋, 🏞
 #set text(size: 10pt, 12pt)
 
 ---
-// Error: 11-31 unexpected argument
+// Error: 11-31 unexpected argument: something
 #set text(something: "invalid")
diff --git a/tests/typ/visualize/shape-circle.typ b/tests/typ/visualize/shape-circle.typ
index cde4b112c..34238d9a4 100644
--- a/tests/typ/visualize/shape-circle.typ
+++ b/tests/typ/visualize/shape-circle.typ
@@ -54,5 +54,5 @@ Expanded by height.
 
 ---
 // Radius wins over width and height.
-// Error: 23-34 unexpected argument
+// Error: 23-34 unexpected argument: width
 #circle(radius: 10pt, width: 50pt, height: 100pt, fill: eastern)
diff --git a/tests/typ/visualize/shape-square.typ b/tests/typ/visualize/shape-square.typ
index cb6552e48..a321dc4a6 100644
--- a/tests/typ/visualize/shape-square.typ
+++ b/tests/typ/visualize/shape-square.typ
@@ -35,5 +35,5 @@
 
 ---
 // Size wins over width and height.
-// Error: 09-20 unexpected argument
+// Error: 09-20 unexpected argument: width
 #square(width: 10cm, height: 20cm, size: 1cm, fill: rgb("eb5278"))