diff --git a/apkverity/src/loopdevice/sys.rs b/apkverity/src/loopdevice/sys.rs
index 2d4977b..3f10f22 100644
--- a/apkverity/src/loopdevice/sys.rs
+++ b/apkverity/src/loopdevice/sys.rs
@@ -24,6 +24,7 @@
 
 pub const LOOP_CTL_GET_FREE: libc::c_ulong = 0x4C82;
 pub const LOOP_CONFIGURE: libc::c_ulong = 0x4C0A;
+#[cfg(test)]
 pub const LOOP_CLR_FD: libc::c_ulong = 0x4C01;
 
 #[repr(C)]