diff --git a/src/flags.rs b/src/flags.rs
index 0a9e64a..e2bfb65 100644
--- a/src/flags.rs
+++ b/src/flags.rs
@@ -194,6 +194,7 @@ static DEFAULT_RUSTFLAGS: &[&[&str]] = &[
         "-Zsanitizer=cfi",
         "-Clto",
         "-Zsanitizer-cfi-normalize-integers",
+        "-Ccodegen-units=1",
         "-ocodegen",
         "-Cdebuginfo=2",
         "-Copt-level=3",
@@ -693,6 +694,7 @@ static EXPENSIVE_RUSTFLAGS: &[&[&str]] = &[
         "-Cdebuginfo=2",
         "-Copt-level=3",
         "-Zsanitizer=cfi",
+        "-Ccodegen-units=1",
         "-Clto",
         "-ocodegen",
         "-Zsanitizer-cfi-normalize-integers",