diff --git a/Cargo.toml b/Cargo.toml
index 84ed8d6..451c6e6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@ crate-type = ["rlib", "cdylib", "staticlib"]
 [features]
 default = ["ffi", "crc"]
 
-ffi = ["malloc-array"]
+ffi = ["libc", "malloc-array"]
 
 [profile.release]
 opt-level = 3
@@ -24,7 +24,7 @@ panic = "unwind"
 [dependencies]
 sha2 = "0.9"
 malloc-array = {version = "1.4", optional=true}
-libc = "0.2"
+libc = {version = "0.2", optional=true}
 crc = {version = "1.8", optional=true}
 hex-literal = "0.2"
 getrandom = "0.1"
diff --git a/src/lib.rs b/src/lib.rs
index 360b885..8830b08 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -237,6 +237,7 @@ pub fn generate<T: AsRef<[u8]>>(context: &ctx::Context, bytes: T) -> Result<Stri
 }
 
 use std::ffi::c_void;
+#[cfg(feature="ffi")] 
 use libc::{
     size_t,
     c_char,