diff --git a/assembly/src/ast/ident.rs b/assembly/src/ast/ident.rs
index 0f7e594c8..ea2d13a23 100644
--- a/assembly/src/ast/ident.rs
+++ b/assembly/src/ast/ident.rs
@@ -12,8 +12,8 @@ use crate::{SourceSpan, Span, Spanned};
 pub enum IdentError {
     #[error("invalid identifier: cannot be empty")]
     Empty,
-    #[error("invalid identifier: must contain only lowercase, ascii alphanumeric characters, or underscores")]
-    InvalidChars,
+    #[error("invalid identifier '{ident}': must contain only lowercase, ascii alphanumeric characters, or underscores")]
+    InvalidChars { ident: Arc<str> },
     #[error("invalid identifier: must start with lowercase ascii alphabetic character")]
     InvalidStart,
     #[error("invalid identifier: length exceeds the maximum of {max} bytes")]
@@ -109,7 +109,7 @@ impl Ident {
             return Err(IdentError::InvalidStart);
         }
         if !source.chars().all(|c| c.is_ascii_alphabetic() || matches!(c, '_' | '0'..='9')) {
-            return Err(IdentError::InvalidChars);
+            return Err(IdentError::InvalidChars { ident: source.into() });
         }
         Ok(())
     }
diff --git a/assembly/src/ast/procedure/name.rs b/assembly/src/ast/procedure/name.rs
index f7979bd42..731610aaf 100644
--- a/assembly/src/ast/procedure/name.rs
+++ b/assembly/src/ast/procedure/name.rs
@@ -298,17 +298,17 @@ impl FromStr for ProcedureName {
                     match c {
                         '"' => {
                             if chars.next().is_some() {
-                                break Err(IdentError::InvalidChars);
+                                break Err(IdentError::InvalidChars { ident: s.into() });
                             }
                             let tok = &s[1..pos];
                             break Ok(Arc::from(tok.to_string().into_boxed_str()));
                         },
                         c if c.is_alphanumeric() => continue,
                         '_' | '$' | '-' | '!' | '?' | '<' | '>' | ':' | '.' => continue,
-                        _ => break Err(IdentError::InvalidChars),
+                        _ => break Err(IdentError::InvalidChars { ident: s.into() }),
                     }
                 } else {
-                    break Err(IdentError::InvalidChars);
+                    break Err(IdentError::InvalidChars { ident: s.into() });
                 }
             },
             Some((_, c)) if c.is_ascii_lowercase() || c == '_' || c == '$' => {
@@ -317,13 +317,13 @@ impl FromStr for ProcedureName {
                     '_' | '$' => false,
                     _ => true,
                 }) {
-                    Err(IdentError::InvalidChars)
+                    Err(IdentError::InvalidChars { ident: s.into() })
                 } else {
                     Ok(Arc::from(s.to_string().into_boxed_str()))
                 }
             },
             Some((_, c)) if c.is_ascii_uppercase() => Err(IdentError::Casing(CaseKindError::Snake)),
-            Some(_) => Err(IdentError::InvalidChars),
+            Some(_) => Err(IdentError::InvalidChars { ident: s.into() }),
         }?;
         Ok(Self(Ident::new_unchecked(Span::unknown(raw))))
     }
diff --git a/assembly/src/library/path.rs b/assembly/src/library/path.rs
index 22e5fe847..8175339dd 100644
--- a/assembly/src/library/path.rs
+++ b/assembly/src/library/path.rs
@@ -575,7 +575,10 @@ mod tests {
         assert_matches!(path, Err(PathError::InvalidComponent(IdentError::InvalidStart)));
 
         let path = LibraryPath::new("foo::b@r");
-        assert_matches!(path, Err(PathError::InvalidComponent(IdentError::InvalidChars)));
+        assert_matches!(
+            path,
+            Err(PathError::InvalidComponent(IdentError::InvalidChars { ident: _ }))
+        );
 
         let path = LibraryPath::new("#foo::bar");
         assert_matches!(