diff --git a/dropshot/tests/fail/bad_trait_channel21.stderr b/dropshot/tests/fail/bad_trait_channel21.stderr
index de1a8b9e..b994b0f0 100644
--- a/dropshot/tests/fail/bad_trait_channel21.stderr
+++ b/dropshot/tests/fail/bad_trait_channel21.stderr
@@ -25,11 +25,13 @@ error: functions cannot be both `async` and C-variadic
 32 |         ...
    |         ^^^ C-variadic because of this
 
-error: associated functions cannot have a C variable argument list
+error: `...` is not supported for non-extern functions
   --> tests/fail/bad_trait_channel21.rs:32:9
    |
 32 |         ...
    |         ^^^
+   |
+   = help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
 
 error: functions cannot be both `async` and C-variadic
   --> tests/fail/bad_trait_channel21.rs:42:5
@@ -40,11 +42,13 @@ error: functions cannot be both `async` and C-variadic
 45 |         ...
    |         ^^^ C-variadic because of this
 
-error: associated functions cannot have a C variable argument list
+error: `...` is not supported for non-extern functions
   --> tests/fail/bad_trait_channel21.rs:45:9
    |
 45 |         ...
    |         ^^^
+   |
+   = help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
 
 error[E0658]: C-variadic functions are unstable
   --> tests/fail/bad_trait_channel21.rs:29:5
diff --git a/dropshot/tests/fail/bad_trait_endpoint21.stderr b/dropshot/tests/fail/bad_trait_endpoint21.stderr
index 594b0089..fa5bd605 100644
--- a/dropshot/tests/fail/bad_trait_endpoint21.stderr
+++ b/dropshot/tests/fail/bad_trait_endpoint21.stderr
@@ -28,11 +28,13 @@ error: functions cannot be both `async` and C-variadic
 33 |         ...
    |         ^^^ C-variadic because of this
 
-error: associated functions cannot have a C variable argument list
+error: `...` is not supported for non-extern functions
   --> tests/fail/bad_trait_endpoint21.rs:33:9
    |
 33 |         ...
    |         ^^^
+   |
+   = help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
 
 error: functions cannot be both `async` and C-variadic
   --> tests/fail/bad_trait_endpoint21.rs:43:5
@@ -43,11 +45,13 @@ error: functions cannot be both `async` and C-variadic
 46 |         ...
    |         ^^^ C-variadic because of this
 
-error: associated functions cannot have a C variable argument list
+error: `...` is not supported for non-extern functions
   --> tests/fail/bad_trait_endpoint21.rs:46:9
    |
 46 |         ...
    |         ^^^
+   |
+   = help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
 
 error[E0658]: C-variadic functions are unstable
   --> tests/fail/bad_trait_endpoint21.rs:30:5
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 36e42c44..ba3ebb05 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -4,5 +4,5 @@
 # The intent is to keep this updated as new stable versions are relased.
 
 [toolchain]
-channel = "1.91.1"
+channel = "1.92.0"
 profile = "default"