diff --git a/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.rs b/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.rs
index c6c196db6f2a6..79e9834b54ed2 100644
--- a/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.rs
+++ b/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.rs
@@ -16,7 +16,6 @@ fn use_dyn<const N: usize>(v: &dyn Foo<N>) where [u8; N + 1]: Sized {
 }
 
 fn main() {
-    // FIXME(generic_const_exprs): Improve the error message here.
     use_dyn(&());
     //~^ ERROR type annotations needed
 }
diff --git a/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.stderr b/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.stderr
index ce75314ada769..59e9fee1eaf41 100644
--- a/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.stderr
+++ b/src/test/ui/const-generics/generic_const_exprs/object-safety-ok-infer-err.stderr
@@ -1,14 +1,18 @@
-error[E0284]: type annotations needed: cannot satisfy `the constant `use_dyn::<{_: usize}>::{constant#0}` can be evaluated`
-  --> $DIR/object-safety-ok-infer-err.rs:20:5
+error[E0284]: type annotations needed
+  --> $DIR/object-safety-ok-infer-err.rs:19:5
    |
 LL |     use_dyn(&());
-   |     ^^^^^^^ cannot satisfy `the constant `use_dyn::<{_: usize}>::{constant#0}` can be evaluated`
+   |     ^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `use_dyn`
    |
 note: required by a bound in `use_dyn`
   --> $DIR/object-safety-ok-infer-err.rs:14:55
    |
 LL | fn use_dyn<const N: usize>(v: &dyn Foo<N>) where [u8; N + 1]: Sized {
    |                                                       ^^^^^ required by this bound in `use_dyn`
+help: consider specifying the generic argument
+   |
+LL |     use_dyn::<N>(&());
+   |            +++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.rs b/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.rs
index ed81c01bb1726..7a78e0f109ca7 100644
--- a/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.rs
+++ b/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.rs
@@ -7,5 +7,5 @@ extern crate generics_of_parent_impl_trait;
 fn main() {
     // check for `impl Trait<{ const }>` which has a parent of a `DefKind::TyParam`
     generics_of_parent_impl_trait::foo([()]);
-    //~^ error: type annotations needed:
+    //~^ error: type annotations needed
 }
diff --git a/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.stderr b/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.stderr
index 99085711513d8..87ff7babe71c0 100644
--- a/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.stderr
+++ b/src/test/ui/const-generics/parent_generics_of_encoding_impl_trait.stderr
@@ -1,8 +1,8 @@
-error[E0284]: type annotations needed: cannot satisfy `the constant `foo::{opaque#0}::{constant#0}` can be evaluated`
+error[E0284]: type annotations needed
   --> $DIR/parent_generics_of_encoding_impl_trait.rs:9:5
    |
 LL |     generics_of_parent_impl_trait::foo([()]);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot satisfy `the constant `foo::{opaque#0}::{constant#0}` can be evaluated`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of const parameter `N` declared on the function `foo`
    |
 note: required by a bound in `foo`
   --> $DIR/auxiliary/generics_of_parent_impl_trait.rs:6:48