diff --git a/docs/src/rust-feature-support/intrinsics.md b/docs/src/rust-feature-support/intrinsics.md
index 501a9952f05e..f97db5d8ab6c 100644
--- a/docs/src/rust-feature-support/intrinsics.md
+++ b/docs/src/rust-feature-support/intrinsics.md
@@ -187,8 +187,8 @@ nontemporal_store | No | |
 offset | Partial | Doesn't check [all UB conditions](https://doc.rust-lang.org/std/primitive.pointer.html#safety-2) |
 powf32 | Partial | Results are overapproximated |
 powf64 | Partial | Results are overapproximated |
-powif32 | No | |
-powif64 | No | |
+powif32 | Partial | Results are overapproximated |
+powif64 | Partial | Results are overapproximated |
 pref_align_of | Yes | |
 prefetch_read_data | No | |
 prefetch_read_instruction | No | |
diff --git a/kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs b/kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs
index 12352190e6e2..91f7ea20c9b1 100644
--- a/kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs
+++ b/kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs
@@ -490,8 +490,8 @@ impl<'tcx> GotocCtx<'tcx> {
             ),
             "powf32" => codegen_simple_intrinsic!(Powf),
             "powf64" => codegen_simple_intrinsic!(Pow),
-            "powif32" => unstable_codegen!(codegen_simple_intrinsic!(Powif)),
-            "powif64" => unstable_codegen!(codegen_simple_intrinsic!(Powi)),
+            "powif32" => codegen_simple_intrinsic!(Powif),
+            "powif64" => codegen_simple_intrinsic!(Powi),
             "pref_align_of" => codegen_intrinsic_const!(),
             "ptr_guaranteed_cmp" => self.codegen_ptr_guaranteed_cmp(fargs, place, loc),
             "ptr_offset_from" => self.codegen_ptr_offset_from(fargs, place, loc),
diff --git a/tests/kani/Cast/cast_abstract_args_to_concrete_fixme2.rs b/tests/kani/Cast/cast_abstract_args_to_concrete.rs
similarity index 92%
rename from tests/kani/Cast/cast_abstract_args_to_concrete_fixme2.rs
rename to tests/kani/Cast/cast_abstract_args_to_concrete.rs
index 51067e0e0a73..6694f799493a 100644
--- a/tests/kani/Cast/cast_abstract_args_to_concrete_fixme2.rs
+++ b/tests/kani/Cast/cast_abstract_args_to_concrete.rs
@@ -1,9 +1,6 @@
 // Copyright Kani Contributors
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
-// https://github.com/model-checking/kani/issues/555
-// kani-flags: --no-undefined-function-checks
-
 // This regression test is in response to issue #135.
 // The type of the second parameter to powi is a `CInteger`, but
 // the type of `2` here is a `u32`. This test ensures that
diff --git a/tests/kani/Cast/cast_abstract_args_to_concrete_fixme.rs b/tests/kani/Cast/cast_abstract_args_to_concrete_fixme.rs
deleted file mode 100644
index faeb74c5d66a..000000000000
--- a/tests/kani/Cast/cast_abstract_args_to_concrete_fixme.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright Kani Contributors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! This test is a modified version of cast_abstract_args_to_concrete_fixme.rs.
-//! The original test requires --no-undefined-function-checks to pass. This is an issue that
-//! require investigation. See https://github.com/model-checking/kani/issues/555.
-//!
-//! Once this issue is fixed. Please remove this test and remove the kani flag from the original
-//! test: --no-undefined-function-check
-
-fn main() {
-    let _x32 = 1.0f32.powi(2);
-    let _x64 = 1.0f64.powi(2);
-
-    unsafe {
-        let size: libc::size_t = mem::size_of::<i32>();
-        let my_num: *mut libc::c_void = libc::malloc(size);
-        if my_num.is_null() {
-            panic!("failed to allocate memory");
-        }
-        let my_num2 = libc::memset(my_num, 1, size);
-        libc::free(my_num);
-    }
-}
diff --git a/tests/kani/Intrinsics/Math/Arith/powi.rs b/tests/kani/Intrinsics/Math/Arith/powi.rs
new file mode 100644
index 000000000000..c7986d18a9ef
--- /dev/null
+++ b/tests/kani/Intrinsics/Math/Arith/powi.rs
@@ -0,0 +1,22 @@
+// Copyright Kani Contributors
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[kani::proof]
+fn verify_powi32() {
+    let x: f32 = kani::any();
+    kani::assume(x.is_normal());
+    kani::assume(x >= 1e-19 || x <= -1e-19);
+    kani::assume(x <= 1.84e19 && x >= -1.84e19);
+    let x2 = x.powi(2);
+    assert!(x2 >= 0.0);
+}
+
+#[kani::proof]
+fn verify_powi64() {
+    let x: f64 = kani::any();
+    kani::assume(x.is_normal());
+    kani::assume(x >= 1e-153 || x <= -1e-153);
+    kani::assume(x <= 1.34e154 && x >= -1.34e154);
+    let x2 = x.powi(2);
+    assert!(x2 >= 0.0);
+}