diff --git a/src/infra/infra_secrets.erl b/src/infra/infra_secrets.erl
index 6fe7fd3..b6d55c0 100644
--- a/src/infra/infra_secrets.erl
+++ b/src/infra/infra_secrets.erl
@@ -51,7 +51,7 @@ require_admin_seed_email(EnvKey) ->
   case os:getenv(EnvKey) of
     false -> {error, {missing_secret, list_to_atom(EnvKey)}};
     "" -> {error, {missing_secret, list_to_atom(EnvKey)}};
-    Email -> {ok, list_to_binary(Email)}
+    Email -> {ok, env_to_binary(Email)}
   end.
 
 -spec require_admin_seed_password(string()) ->
@@ -61,7 +61,7 @@ require_admin_seed_password(EnvKey) ->
     false -> {error, {missing_secret, list_to_atom(EnvKey)}};
     "" -> {error, {missing_secret, list_to_atom(EnvKey)}};
     Pass ->
-      Bin = list_to_binary(Pass),
+      Bin = env_to_binary(Pass),
       case is_strong_secret(Bin) of
         true -> {ok, Bin};
         false -> {error, {weak_secret, list_to_atom(EnvKey)}}
@@ -124,9 +124,13 @@ os_getenv_binary(Key) ->
   case os:getenv(Key) of
     false -> undefined;
     "" -> undefined;
-    Val -> list_to_binary(Val)
+    Val -> env_to_binary(Val)
   end.
 
+%% os:getenv/1 returns Unicode charlists; list_to_binary/1 only accepts byte iolists.
+env_to_binary(Val) when is_binary(Val) -> Val;
+env_to_binary(Val) when is_list(Val) -> unicode:characters_to_binary(Val).
+
 dev_warn_if_weak(_Name, undefined) -> ok;
 dev_warn_if_weak(Name, Secret) ->
   case is_strong_secret(Secret) of
diff --git a/test/unit/infra_secrets_tests.erl b/test/unit/infra_secrets_tests.erl
index 61e4263..5816b91 100644
--- a/test/unit/infra_secrets_tests.erl
+++ b/test/unit/infra_secrets_tests.erl
@@ -26,7 +26,8 @@ infra_secrets_test_() ->
     {"stage rejects missing JWT_SECRET", fun test_stage_missing_jwt/0},
     {"stage rejects weak JWT_SECRET", fun test_stage_weak_jwt/0},
     {"stage accepts strong secrets", fun test_stage_strong_ok/0},
-    {"require_admin_seed_password rejects 123456", fun test_weak_admin_password/0}
+    {"require_admin_seed_password rejects 123456", fun test_weak_admin_password/0},
+    {"require_admin_seed_password rejects cyrillic placeholder", fun test_cyrillic_placeholder_password/0}
   ]}.
 
 test_dev_missing_ok() ->
@@ -60,3 +61,8 @@ test_weak_admin_password() ->
   os:putenv("ADMIN_PASSWORD", "123456"),
   ?assertMatch({error, {weak_secret, 'ADMIN_PASSWORD'}},
     infra_secrets:require_admin_seed_password("ADMIN_PASSWORD")).
+
+test_cyrillic_placeholder_password() ->
+  os:putenv("ADMIN_PASSWORD", "замените"),
+  ?assertMatch({error, {weak_secret, 'ADMIN_PASSWORD'}},
+    infra_secrets:require_admin_seed_password("ADMIN_PASSWORD")).