diff --git a/Cargo.toml b/Cargo.toml
index 4638903..d365f6b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,11 +15,11 @@ rust-version = "1.70.0"
 
 [dependencies]
 rusty_ffmpeg = "0.14.0"
-libc = "0.2"
 paste = "1.0"
 thiserror = "1.0"
 
 [dev-dependencies]
+libc = "0.2"
 anyhow = "1.0.57"
 cstr = "0.2.11"
 once_cell = "1.12.0"
diff --git a/src/avcodec/codec.rs b/src/avcodec/codec.rs
index c22d300..6b1de33 100644
--- a/src/avcodec/codec.rs
+++ b/src/avcodec/codec.rs
@@ -79,26 +79,35 @@ impl Iterator for AVCodecIter {
 }
 
 impl<'codec> AVCodec {
-    /// Convenient function for probing a pointer until met specific memory
-    /// pattern.
-    fn probe_len<T>(mut ptr: *const T, tail: T) -> usize {
+    /// Probing specific memory pattern and return the offset.
+    ///
+    /// # Safety
+    /// ptr needs to be terminated by tail
+    unsafe fn probe_len<T>(mut ptr: *const T, tail: T) -> usize {
         for len in 0.. {
-            if unsafe { libc::memcmp(ptr as _, &tail as *const _ as _, mem::size_of::<T>()) } == 0 {
+            let left = ptr as *const u8;
+            let left = unsafe { slice::from_raw_parts(left, mem::size_of::<T>()) };
+            let right = &tail as *const _ as *const u8;
+            let right = unsafe { slice::from_raw_parts(right, mem::size_of::<T>()) };
+            if left == right {
                 return len;
             }
             unsafe {
                 ptr = ptr.add(1);
             }
         }
-        unreachable!()
+        usize::MAX
     }
 
-    /// Convenient function for building a memory slice.
-    fn build_array<'a, T>(ptr: *const T, tail: T) -> Option<&'a [T]> {
+    /// Building a memory slice ends begin with `ptr` and ends with given `tail`.
+    ///
+    /// # Safety
+    /// ptr needs to be terminated by tail
+    unsafe fn build_array<'a, T>(ptr: *const T, tail: T) -> Option<&'a [T]> {
         if ptr.is_null() {
             None
         } else {
-            let len = Self::probe_len(ptr, tail);
+            let len = unsafe { Self::probe_len(ptr, tail) };
             Some(unsafe { slice::from_raw_parts(ptr, len) })
         }
     }
@@ -106,25 +115,25 @@ impl<'codec> AVCodec {
     /// Return supported framerates of this [`AVCodec`].
     pub fn supported_framerates(&'codec self) -> Option<&'codec [AVRational]> {
         // terminates with AVRational{0, 0}
-        Self::build_array(self.supported_framerates, AVRational { den: 0, num: 0 })
+        unsafe { Self::build_array(self.supported_framerates, AVRational { den: 0, num: 0 }) }
     }
 
     /// Return supported pix_fmts of this [`AVCodec`].
     pub fn pix_fmts(&'codec self) -> Option<&'codec [AVPixelFormat]> {
         // terminates with -1
-        Self::build_array(self.pix_fmts, -1)
+        unsafe { Self::build_array(self.pix_fmts, -1) }
     }
 
     /// Return supported samplerates of this [`AVCodec`].
     pub fn supported_samplerates(&'codec self) -> Option<&'codec [i32]> {
         // terminates with 0
-        Self::build_array(self.supported_samplerates, 0)
+        unsafe { Self::build_array(self.supported_samplerates, 0) }
     }
 
     /// Return supported sample_fmts of this [`AVCodec`].
     pub fn sample_fmts(&'codec self) -> Option<&'codec [ffi::AVSampleFormat]> {
         // terminates with -1
-        Self::build_array(self.sample_fmts, -1)
+        unsafe { Self::build_array(self.sample_fmts, -1) }
     }
 }
 
diff --git a/src/avutil/buffer.rs b/src/avutil/buffer.rs
index a121ec4..65e3744 100644
--- a/src/avutil/buffer.rs
+++ b/src/avutil/buffer.rs
@@ -2,7 +2,7 @@ use crate::{
     ffi,
     shared::{PointerUpgrade, RetUpgrade},
 };
-use libc::c_int;
+use std::os::raw::c_int;
 
 wrap!(AVBufferRef: ffi::AVBufferRef);
 
diff --git a/src/avutil/channel_layout.rs b/src/avutil/channel_layout.rs
index 745b709..eb06ff8 100644
--- a/src/avutil/channel_layout.rs
+++ b/src/avutil/channel_layout.rs
@@ -3,10 +3,10 @@ use crate::{
     ffi,
     shared::{PointerUpgrade, RetUpgrade},
 };
-use libc::c_void;
 use std::{
     ffi::{CStr, CString},
     mem::MaybeUninit,
+    os::raw::c_void,
     ptr::NonNull,
 };
 
diff --git a/src/avutil/dict.rs b/src/avutil/dict.rs
index ce4a6f9..eda6f9c 100644
--- a/src/avutil/dict.rs
+++ b/src/avutil/dict.rs
@@ -2,6 +2,7 @@ use crate::{error::Result, ffi, shared::*};
 
 use std::{
     ffi::{CStr, CString},
+    os::raw::c_void,
     ptr::{self, NonNull},
 };
 
@@ -120,7 +121,7 @@ impl AVDictionary {
             .upgrade()?;
         let result = unsafe { CStr::from_ptr(s).to_owned() };
         unsafe {
-            ffi::av_freep(&mut s as *mut _ as *mut libc::c_void);
+            ffi::av_freep(&mut s as *mut _ as *mut c_void);
         }
         Ok(result)
     }
diff --git a/src/avutil/frame.rs b/src/avutil/frame.rs
index 3b0d918..ade4017 100644
--- a/src/avutil/frame.rs
+++ b/src/avutil/frame.rs
@@ -5,7 +5,7 @@ use crate::{
     shared::*,
 };
 
-use std::{fmt, mem::size_of, ptr::NonNull, slice};
+use std::{fmt, mem::size_of, os::raw::c_int, ptr::NonNull, slice};
 
 wrap!(AVFrame: ffi::AVFrame);
 settable!(AVFrame {
@@ -93,7 +93,7 @@ impl AVFrame {
         unsafe { &mut self.deref_mut().data }
     }
 
-    pub fn linesize_mut(&mut self) -> &mut [libc::c_int; 8] {
+    pub fn linesize_mut(&mut self) -> &mut [c_int; 8] {
         unsafe { &mut self.deref_mut().linesize }
     }
 
diff --git a/src/avutil/rational.rs b/src/avutil/rational.rs
index a9bd295..4c6df4b 100644
--- a/src/avutil/rational.rs
+++ b/src/avutil/rational.rs
@@ -1,3 +1,5 @@
+use std::os::raw::c_int;
+
 use crate::ffi;
 
 pub use ffi::AVRational;
@@ -15,7 +17,7 @@ pub use ffi::{av_cmp_q, av_inv_q, av_make_q, av_q2d};
 ///
 /// `d` - double to convert
 /// `max` - Maximum allowed numerator and denominator
-pub fn av_d2q(d: f64, max: libc::c_int) -> AVRational {
+pub fn av_d2q(d: f64, max: c_int) -> AVRational {
     unsafe { ffi::av_d2q(d, max) }
 }
 
@@ -49,7 +51,7 @@ pub fn av_sub_q(b: AVRational, c: AVRational) -> AVRational {
 /// Return `1` if `q1` is nearer to `q` than `q2`.
 /// `-1` if `q2` is nearer to `q` than `q1`.
 /// `0` if they have the same distance.
-pub fn av_nearer_q(q: AVRational, q1: AVRational, q2: AVRational) -> libc::c_int {
+pub fn av_nearer_q(q: AVRational, q1: AVRational, q2: AVRational) -> c_int {
     unsafe { ffi::av_nearer_q(q, q1, q2) }
 }
 
@@ -63,7 +65,7 @@ pub fn av_q2intfloat(q: AVRational) -> u32 {
 #[inline]
 /// Return the best rational so that a and b are multiple of it. If the
 /// resulting denominator is larger than max_den, return def.
-pub fn av_gcd_q(a: AVRational, b: AVRational, max_den: libc::c_int, def: AVRational) -> AVRational {
+pub fn av_gcd_q(a: AVRational, b: AVRational, max_den: c_int, def: AVRational) -> AVRational {
     unsafe { ffi::av_gcd_q(a, b, max_den, def) }
 }
 
diff --git a/src/error.rs b/src/error.rs
index 7cffa5a..0217b65 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,8 +1,8 @@
 //! Errors of the rsmpeg.
-use libc::c_int;
 use std::{
     cmp::{Eq, PartialEq},
     num::TryFromIntError,
+    os::raw::c_int,
 };
 use thiserror::Error;
 
diff --git a/src/shared/mod.rs b/src/shared/mod.rs
index c703864..a1d3edd 100644
--- a/src/shared/mod.rs
+++ b/src/shared/mod.rs
@@ -1,8 +1,7 @@
 //! Internal shared convenient things.
 use crate::error::{Result, Ret, RsmpegError};
-use libc::c_int;
 use rusty_ffmpeg::ffi;
-use std::{ops::Deref, ptr::NonNull};
+use std::{ops::Deref, os::raw::c_int, ptr::NonNull};
 
 /// Triage a pointer to Some(non-null) or None
 pub trait PointerUpgrade<T>: Sized {