diff --git a/src/cargo/core/gc.rs b/src/cargo/core/gc.rs
index 9d63c177b94..2a8f4267a8f 100644
--- a/src/cargo/core/gc.rs
+++ b/src/cargo/core/gc.rs
@@ -478,7 +478,7 @@ pub fn parse_human_size(input: &str) -> CargoResult<u64> {
             "kib" => 1024.0,
             "mib" => 1024.0 * 1024.0,
             "gib" => 1024.0 * 1024.0 * 1024.0,
-            s => panic!("suffix `{s}` out of sync with regex"),
+            s => unreachable!("suffix `{s}` out of sync with regex"),
         },
         None => {
             return cap[1]