diff --git a/fuzz/fuzz_targets/ion.rs b/fuzz/fuzz_targets/ion.rs
index 1334938..288b8fb 100644
--- a/fuzz/fuzz_targets/ion.rs
+++ b/fuzz/fuzz_targets/ion.rs
@@ -12,5 +12,5 @@ fuzz_target!(|func: Func| {
     let _ = env_logger::try_init();
     log::debug!("func:\n{:?}", func);
     let env = regalloc2::fuzzing::func::machine_env();
-    let _out = regalloc2::ion::run(&func, &env).expect("regalloc did not succeed");
+    let _out = regalloc2::ion::run(&func, &env, false).expect("regalloc did not succeed");
 });
diff --git a/fuzz/fuzz_targets/ion_checker.rs b/fuzz/fuzz_targets/ion_checker.rs
index da43dbc..f6e8cd5 100644
--- a/fuzz/fuzz_targets/ion_checker.rs
+++ b/fuzz/fuzz_targets/ion_checker.rs
@@ -4,11 +4,11 @@
  */
 
 #![no_main]
+use libfuzzer_sys::arbitrary::{Arbitrary, Result, Unstructured};
 use libfuzzer_sys::fuzz_target;
-use libfuzzer_sys::arbitrary::{Arbitrary, Unstructured, Result};
 
-use regalloc2::fuzzing::func::{Func, Options};
 use regalloc2::checker::Checker;
+use regalloc2::fuzzing::func::{Func, Options};
 
 #[derive(Clone, Debug)]
 struct TestCase {
@@ -18,16 +18,19 @@ struct TestCase {
 impl Arbitrary for TestCase {
     fn arbitrary(u: &mut Unstructured) -> Result<TestCase> {
         Ok(TestCase {
-            func: Func::arbitrary_with_options(u, &Options {
-                reused_inputs: true,
-                fixed_regs: true,
-                clobbers: true,
-                control_flow: true,
-                reducible: false,
-                block_params: true,
-                always_local_uses: false,
-                reftypes: true,
-            })?,
+            func: Func::arbitrary_with_options(
+                u,
+                &Options {
+                    reused_inputs: true,
+                    fixed_regs: true,
+                    clobbers: true,
+                    control_flow: true,
+                    reducible: false,
+                    block_params: true,
+                    always_local_uses: false,
+                    reftypes: true,
+                },
+            )?,
         })
     }
 }
@@ -37,7 +40,7 @@ fuzz_target!(|testcase: TestCase| {
     let _ = env_logger::try_init();
     log::debug!("func:\n{:?}", func);
     let env = regalloc2::fuzzing::func::machine_env();
-    let out = regalloc2::ion::run(&func, &env).expect("regalloc did not succeed");
+    let out = regalloc2::ion::run(&func, &env, true).expect("regalloc did not succeed");
 
     let mut checker = Checker::new(&func);
     checker.prepare(&out);
diff --git a/fuzz/fuzz_targets/ssagen.rs b/fuzz/fuzz_targets/ssagen.rs
index c0ff306..d68d672 100644
--- a/fuzz/fuzz_targets/ssagen.rs
+++ b/fuzz/fuzz_targets/ssagen.rs
@@ -37,6 +37,6 @@ impl Arbitrary for TestCase {
 }
 
 fuzz_target!(|t: TestCase| {
-    let cfginfo = CFGInfo::new(&t.f);
+    let cfginfo = CFGInfo::new(&t.f).expect("could not create CFG info");
     validate_ssa(&t.f, &cfginfo).expect("invalid SSA");
 });