diff --git a/src/unix/newlib/espidf/mod.rs b/src/unix/newlib/espidf/mod.rs
index 4e3898153357..1ac5113c917b 100644
--- a/src/unix/newlib/espidf/mod.rs
+++ b/src/unix/newlib/espidf/mod.rs
@@ -1,7 +1,7 @@
 use crate::prelude::*;
 
 pub type clock_t = c_ulong;
-pub type c_char = i8;
+pub type c_char = u8;
 pub type wchar_t = u32;
 
 pub type c_long = i32;