diff --git a/lib/asm.ts b/lib/asm.ts
index a09edba..5ba4fe7 100644
--- a/lib/asm.ts
+++ b/lib/asm.ts
@@ -136,6 +136,12 @@ export const convertASM_SSA_Unary = (state: ASMState, ssa: SSAUnary): void => {
             )
             break
 
+        case '~':
+            state.insns.push(
+                `CPL`
+            )
+            break
+
         default:
             throw new Error(`unsupported unary op \`'${ssa.op}`)
     }