diff --git a/src/opt/simplify_cfg.rs b/src/opt/simplify_cfg.rs
index 6f4be0c..a3764c9 100644
--- a/src/opt/simplify_cfg.rs
+++ b/src/opt/simplify_cfg.rs
@@ -136,6 +136,8 @@ impl Optimize<FunctionDefinition> for SimplifyCfgMerge {
             }
         }
 
+        code.blocks.retain(|bid, _| !merged_to.contains_key(bid));
+
         for (bid, block) in &mut code.blocks {
             for inst in block.instructions.iter_mut() {
                 replace_instruction_operands(inst, &replaces);
@@ -143,7 +145,6 @@ impl Optimize<FunctionDefinition> for SimplifyCfgMerge {
             replace_exit_operands(&mut block.exit, &replaces);
         }
 
-        code.blocks.retain(|bid, _| !merged_to.contains_key(bid));
         !merged_to.is_empty()
     }
 }
@@ -290,25 +291,19 @@ fn replace_instruction_operands(inst: &mut Instruction, replaces: &HashMap<Regis
             replace_operand(lhs, replaces);
             replace_operand(rhs, replaces);
         }
-        Instruction::UnaryOp { operand, .. } => {
-            replace_operand(operand, replaces);
-        }
+        Instruction::UnaryOp { operand, .. } => replace_operand(operand, replaces),
         Instruction::Store { ptr, value } => {
             replace_operand(ptr, replaces);
             replace_operand(value, replaces);
         }
-        Instruction::Load { ptr } => {
-            replace_operand(ptr, replaces);
-        }
+        Instruction::Load { ptr } => replace_operand(ptr, replaces),
         Instruction::Call { callee, args, .. } => {
             replace_operand(callee, replaces);
             for arg in args.iter_mut() {
                 replace_operand(arg, replaces);
             }
         }
-        Instruction::TypeCast { value, .. } => {
-            replace_operand(value, replaces);
-        }
+        Instruction::TypeCast { value, .. } => replace_operand(value, replaces),
         Instruction::GetElementPtr { ptr, offset, .. } => {
             replace_operand(ptr, replaces);
             replace_operand(offset, replaces);