diff --git a/src/bin/cargo/commands/install.rs b/src/bin/cargo/commands/install.rs
index 010a4f48385d..57063f11dc80 100644
--- a/src/bin/cargo/commands/install.rs
+++ b/src/bin/cargo/commands/install.rs
@@ -83,6 +83,7 @@ pub fn cli() -> Command {
             "debug",
             "Build in debug mode (with the 'dev' profile) instead of release mode",
         ))
+        .arg_unsupported_mode("release", "install", "debug")
         .arg_profile("Install artifacts with the specified profile")
         .arg_target_triple("Build for the target triple")
         .arg_target_dir()
diff --git a/src/cargo/util/command_prelude.rs b/src/cargo/util/command_prelude.rs
index 303f965a74e0..270b558c6c2f 100644
--- a/src/cargo/util/command_prelude.rs
+++ b/src/cargo/util/command_prelude.rs
@@ -525,7 +525,7 @@ Run `{cmd}` to see possible targets."
 
         let name = match (
             self.maybe_flag("release"),
-            self.flag("debug"),
+            self.maybe_flag("debug"),
             specified_profile,
         ) {
             (false, false, None) => default,