diff --git a/cargo-test-fuzz/tests/auto_concretize.rs b/cargo-test-fuzz/tests/auto_concretize.rs
index 4c168222..0e6822aa 100644
--- a/cargo-test-fuzz/tests/auto_concretize.rs
+++ b/cargo-test-fuzz/tests/auto_concretize.rs
@@ -2,6 +2,7 @@ use internal::{
     auto_concretize_enabled,
     dirs::{concretizations_directory_from_target, impl_concretizations_directory_from_target},
 };
+use predicates::prelude::*;
 use std::fs::remove_dir_all;
 use testing::{examples, CommandExt};
 
@@ -53,6 +54,10 @@ fn test_fuzz() {
             .unwrap()
             .args(["--no-run"])
             .logged_assert()
-            .success();
+            .success()
+            .stderr(predicate::str::contains(
+                "`auto_concretize` is deprecated and will be removed in the next major version of \
+                 test-fuzz.",
+            ));
     }
 }
diff --git a/macro/src/lib.rs b/macro/src/lib.rs
index b39df163..45f47535 100644
--- a/macro/src/lib.rs
+++ b/macro/src/lib.rs
@@ -272,10 +272,16 @@ fn map_method_or_fn(
         .map(|s| parse_generic_arguments(s, false))
         .or_else(|| {
             #[cfg(feature = "__auto_concretize")]
-            return auto_concretize::unique_concretization(sig)
-                .map(|s| parse_generic_arguments(&s, true))
-                .map_err(|error| concretization_error = Some(error))
-                .ok();
+            {
+                eprintln!(
+                    "`auto_concretize` is deprecated and will be removed in the next major \
+                     version of test-fuzz."
+                );
+                auto_concretize::unique_concretization(sig)
+                    .map(|s| parse_generic_arguments(&s, true))
+                    .map_err(|error| concretization_error = Some(error))
+                    .ok()
+            }
             #[cfg(not(feature = "__auto_concretize"))]
             return None;
         });