diff --git a/src/tools/compiletest/src/json.rs b/src/tools/compiletest/src/json.rs
index dc6d67983c5..a5ff779a4ab 100644
--- a/src/tools/compiletest/src/json.rs
+++ b/src/tools/compiletest/src/json.rs
@@ -74,8 +74,6 @@ struct DiagnosticSpanMacroExpansion {
 struct DiagnosticCode {
     /// The code itself.
     code: String,
-    /// An explanation for the code.
-    explanation: Option<String>,
 }
 
 pub fn rustfix_diagnostics_only(output: &str) -> String {