diff --git a/src/lib.rs b/src/lib.rs
index 9b43eda..62f0b75 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,5 +3,6 @@ mod constraints;
 
 pub mod geom;
 pub mod settings;
+pub mod unit;
 
 pub use settings::Settings;
diff --git a/src/unit.h b/src/unit.h
index 9d24398..6d54e87 100644
--- a/src/unit.h
+++ b/src/unit.h
@@ -9,11 +9,11 @@
 	unit = NULL;            \
 }
 
-typedef enum {
-	UNIT_GLOBAL  = 0,
-	UNIT_MONITOR = 1,
-	UNIT_TAG     = 2,
-} UnitKind;
+typedef unsigned char UnitKind;
+
+#define UNIT_GLOBAL  0
+#define UNIT_MONITOR 1
+#define UNIT_TAG     2
 
 typedef struct Unit *Unit;
 
diff --git a/src/unit.rs b/src/unit.rs
new file mode 100644
index 0000000..41a0fd5
--- /dev/null
+++ b/src/unit.rs
@@ -0,0 +1,29 @@
+use std::os::raw::*;
+
+#[derive(Clone, Copy, Debug)]
+pub enum Kind {
+    Global,
+    Monitor,
+    Tag,
+}
+
+impl Into<c_uchar> for Kind {
+    fn into(self) -> c_uchar {
+        match self {
+            Self::Global => 0,
+            Self::Monitor => 1,
+            Self::Tag => 2,
+        }
+    }
+}
+
+impl From<c_uchar> for Kind {
+    fn from(value: c_uchar) -> Self {
+        match value {
+            0 => Self::Global,
+            1 => Self::Monitor,
+            2 => Self::Tag,
+            _ => panic!("invalid value for type Kind"),
+        }
+    }
+}