diff --git a/Cargo.lock b/Cargo.lock
index edfee67..66b0f6d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -252,9 +252,9 @@ checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
 
 [[package]]
 name = "els"
-version = "0.1.23-nightly.0"
+version = "0.1.23-nightly.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0318245a907791e8519c8d74b9c6d07f8af4f0389c316a07fc558c4f2baa58f"
+checksum = "a10c98bd826f9954de66945f3b9fcdfd042d552725d44ae2ef05960280a06e56"
 dependencies = [
  "erg_common",
  "erg_compiler",
@@ -274,9 +274,9 @@ dependencies = [
 
 [[package]]
 name = "erg_common"
-version = "0.6.11-nightly.0"
+version = "0.6.11-nightly.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0b8ba19d2ef219b9b2b8edcb29cd7059628bc49332495968438a564511f7a34"
+checksum = "3022fd66079dd98cdf7b609f6600b8a66c841c05cc9d87d66b6ad573797a27ab"
 dependencies = [
  "backtrace-on-stack-overflow",
  "hermit-abi",
@@ -286,9 +286,9 @@ dependencies = [
 
 [[package]]
 name = "erg_compiler"
-version = "0.6.11-nightly.0"
+version = "0.6.11-nightly.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5b8f4a9483689cec631d09c7d7a55f7c9714db761b50514478cd5ded75af62b"
+checksum = "4a54e29dc11754d29ca79302d6997d569af7216fd2f5471306d01aa1aaa49498"
 dependencies = [
  "erg_common",
  "erg_parser",
@@ -296,9 +296,9 @@ dependencies = [
 
 [[package]]
 name = "erg_parser"
-version = "0.6.11-nightly.0"
+version = "0.6.11-nightly.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8259ee261c05034b9b4c0c548be4701651c3a54cc4a0c9c25464c700b45f5910"
+checksum = "344c547b69efd08d496ec84ecc4e9250862209965328d773cbe44589c4c8ceb1"
 dependencies = [
  "erg_common",
  "unicode-xid 0.2.4",
@@ -430,9 +430,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.140"
+version = "0.2.141"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99227334921fae1a979cf0bfdfcc6b3e5ce376ef57e16fb6fb3ea2ed6095f80c"
+checksum = "3304a64d199bb964be99741b7a14d26972741915b3649639149b2479bb46f4b5"
 
 [[package]]
 name = "log"
@@ -593,16 +593,16 @@ checksum = "925383efa346730478fb4838dbe9137d2a47675ad789c546d150a6e1dd4ab31c"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.54"
+version = "1.0.56"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e472a104799c74b514a57226160104aa483546de37e839ec50e3c2e41dd87534"
+checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "py2erg"
-version = "0.0.20"
+version = "0.0.21"
 dependencies = [
  "erg_common",
  "erg_compiler",
@@ -611,7 +611,7 @@ dependencies = [
 
 [[package]]
 name = "pylyzer"
-version = "0.0.20"
+version = "0.0.21"
 dependencies = [
  "els",
  "erg_common",
@@ -792,9 +792,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-demangle"
-version = "0.1.22"
+version = "0.1.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d4a36c42d1873f9a77c53bde094f9664d9891bc604a45b4798fd2c389ed12e5b"
+checksum = "d626bb9dae77e28219937af045c257c28bfd3f69333c512553507f5f9798cb76"
 
 [[package]]
 name = "rustpython-parser"
@@ -820,18 +820,18 @@ checksum = "f91339c0467de62360649f8d3e185ca8de4224ff281f66000de5eb2a77a79041"
 
 [[package]]
 name = "serde"
-version = "1.0.159"
+version = "1.0.160"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c04e8343c3daeec41f58990b9d77068df31209f2af111e059e9fe9646693065"
+checksum = "bb2f3770c8bce3bcda7e149193a069a0f4365bda1fa5cd88e03bca26afc1216c"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.159"
+version = "1.0.160"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c614d17805b093df4b147b51339e7e44bf05ef59fba1e45d83500bcfb4d8585"
+checksum = "291a097c63d8497e00160b166a967a4a79c64f3facdd01cbd7502231688d77df"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -840,9 +840,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.95"
+version = "1.0.96"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d721eca97ac802aa7777b701877c8004d950fc142651367300d21c1cc0194744"
+checksum = "057d394a50403bcac12672b2b18fb387ab6d289d957dab67dd201875391e52f1"
 dependencies = [
  "itoa",
  "ryu",
@@ -920,9 +920,9 @@ checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
 name = "syn"
-version = "2.0.12"
+version = "2.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "79d9531f94112cfc3e4c8f5f02cb2b58f72c97b7efd85f70203cc6d8efda5927"
+checksum = "a34fcf3e8b60f57e6a14301a2e916d323af98b0ea63c599441eec8558660c822"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/Cargo.toml b/Cargo.toml
index c6b1dcd..1a21694 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,16 +15,16 @@ members = [
 ]
 
 [workspace.package]
-version = "0.0.20"
+version = "0.0.21"
 authors = ["Shunsuke Shibayama <sbym1346@gmail.com>"]
 license = "MIT OR Apache-2.0"
 edition = "2021"
 repository = "https://github.com/mtshiba/pylyzer"
 
 [workspace.dependencies]
-erg_common = { version = "0.6.11-nightly.0", features = ["py_compat", "els"] }
-erg_compiler = { version = "0.6.11-nightly.0", features = ["py_compat", "els"] }
-els = { version = "0.1.23-nightly.0", features = ["py_compat"] }
+erg_common = { version = "0.6.11-nightly.1", features = ["py_compat", "els"] }
+erg_compiler = { version = "0.6.11-nightly.1", features = ["py_compat", "els"] }
+els = { version = "0.1.23-nightly.1", features = ["py_compat"] }
 rustpython-parser = "0.1.2"
 # erg_compiler = { git = "https://github.com/erg-lang/erg", branch = "main", features = ["py_compat", "els"] }
 # erg_common = { git = "https://github.com/erg-lang/erg", branch = "main", features = ["py_compat", "els"] }
@@ -44,7 +44,7 @@ erg_compiler = { workspace = true }
 erg_common = { workspace = true }
 els = { workspace = true }
 rustpython-parser = { workspace = true }
-py2erg = { version = "0.0.20", path = "./crates/py2erg" }
+py2erg = { version = "0.0.21", path = "./crates/py2erg" }
 
 [lib]
 path = "src/lib.rs"
diff --git a/README.md b/README.md
index ca1d0b8..27ee5fc 100644
--- a/README.md
+++ b/README.md
@@ -104,7 +104,7 @@ pylyzer converts Python ASTs to Erg ASTs and passes them to Erg's type checker.
 * [ ] `Final`
 * [ ] `Annotated`
 * [ ] `TypeAlias`
-* [ ] type assertion (`typing.cast`)
+* [x] type assertion (`typing.cast`)
 * [x] type narrowing (`is`, `isinstance`)
 * [ ] type guard (`TypeGuard`)
 
diff --git a/tests/casting.py b/tests/casting.py
new file mode 100644
index 0000000..3173a35
--- /dev/null
+++ b/tests/casting.py
@@ -0,0 +1,9 @@
+import typing
+
+s = "a"
+
+assert isinstance(s, int)  # ERR
+
+# force cast to int
+i = typing.cast(int, s)
+print(i + 1) # OK
diff --git a/tests/test.rs b/tests/test.rs
index 4a4a542..b31fd0c 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -88,3 +88,8 @@ fn exec_projection() {
 fn exec_narrowing() {
     expect("tests/narrowing.py", 0, 1);
 }
+
+#[test]
+fn exec_casting() {
+    expect("tests/casting.py", 1, 1);
+}