diff --git a/Cargo.toml b/Cargo.toml
index 3f373fdace..6f61e5f95c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,8 @@ path = "jit.rs"
 
 [features]
 disasm = ["yjit?/disasm", "zjit?/disasm"]
-runtime_checks = ["yjit?/runtime_checks", "zjit?/runtime_checks"]
+# TODO(GH-642) Turning this on trips a btest failure.
+runtime_checks = [] # ["yjit?/runtime_checks", "zjit?/runtime_checks"]
 yjit = [ "dep:yjit" ]
 zjit = [ "dep:zjit" ]