diff --git a/src/cargo/util/toml/mod.rs b/src/cargo/util/toml/mod.rs
index 075a46f37a8..16cba3cd3a2 100644
--- a/src/cargo/util/toml/mod.rs
+++ b/src/cargo/util/toml/mod.rs
@@ -2342,6 +2342,11 @@ fn deprecated_underscore<T>(
         warnings.push(format!(
             "unused manifest key `{old_path}` in the `{name}` {kind}"
         ))
+    } else if old.is_some() {
+        let old_path = new_path.replace("-", "_");
+        warnings.push(format!(
+            "`{old_path}` is deprecated in favor of `{new_path}` and will not work in the 2024 edition\n(in the `{name}` {kind})"
+        ))
     }
 }
 
diff --git a/tests/testsuite/bad_config.rs b/tests/testsuite/bad_config.rs
index a8e03d8b86d..e8fb1ad4065 100644
--- a/tests/testsuite/bad_config.rs
+++ b/tests/testsuite/bad_config.rs
@@ -832,10 +832,11 @@ fn dev_dependencies2() {
         .file("a/src/lib.rs", "")
         .build();
     p.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
-",
+[WARNING] `dev_dependencies` is deprecated in favor of `dev-dependencies` and will not work in the 2024 edition
+(in the `foo` package)
+"
         )
         .run();
 }
@@ -906,10 +907,11 @@ fn build_dependencies2() {
         .file("a/src/lib.rs", "")
         .build();
     p.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
-",
+[WARNING] `build_dependencies` is deprecated in favor of `build-dependencies` and will not work in the 2024 edition
+(in the `foo` package)
+"
         )
         .run();
 }
@@ -972,9 +974,10 @@ fn lib_crate_type2() {
         .file("src/lib.rs", "pub fn foo() {}")
         .build();
     p.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
+[WARNING] `crate_type` is deprecated in favor of `crate-type` and will not work in the 2024 edition
+(in the `foo` library target)
 ",
         )
         .run();
@@ -1046,9 +1049,12 @@ fn examples_crate_type2() {
         )
         .build();
     p.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
+[WARNING] `crate_type` is deprecated in favor of `crate-type` and will not work in the 2024 edition
+(in the `ex` example target)
+[WARNING] `crate_type` is deprecated in favor of `crate-type` and will not work in the 2024 edition
+(in the `goodbye` example target)
 ",
         )
         .run();
@@ -1133,10 +1139,11 @@ fn cargo_platform_build_dependencies2() {
         .build();
 
     p.cargo("check")
-        .with_stderr_does_not_contain(
-            "\
-[WARNING] [..]
-",
+        .with_stderr_contains(
+            format!("\
+[WARNING] `build_dependencies` is deprecated in favor of `build-dependencies` and will not work in the 2024 edition
+(in the `{host}` platform target)
+")
         )
         .run();
 }
@@ -1212,10 +1219,11 @@ fn cargo_platform_dev_dependencies2() {
         .build();
 
     p.cargo("check")
-        .with_stderr_does_not_contain(
-            "\
-[WARNING] [..]
-",
+        .with_stderr_contains(
+            format!("\
+[WARNING] `dev_dependencies` is deprecated in favor of `dev-dependencies` and will not work in the 2024 edition
+(in the `{host}` platform target)
+")
         )
         .run();
 }
@@ -1295,10 +1303,11 @@ fn default_features2() {
         .build();
 
     p.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
-",
+[WARNING] `default_features` is deprecated in favor of `default-features` and will not work in the 2024 edition
+(in the `a` dependency)
+"
         )
         .run();
 }
@@ -1364,9 +1373,10 @@ fn proc_macro2() {
         .build();
 
     foo.cargo("check")
-        .with_stderr_does_not_contain(
+        .with_stderr_contains(
             "\
-[WARNING] [..]
+[WARNING] `proc_macro` is deprecated in favor of `proc-macro` and will not work in the 2024 edition
+(in the `foo` library target)
 ",
         )
         .run();