diff --git a/compiler/lowerer.ts b/compiler/lowerer.ts
index ac7e7af..685558b 100644
--- a/compiler/lowerer.ts
+++ b/compiler/lowerer.ts
@@ -15,7 +15,7 @@ export class Lowerer {
     public constructor(private lastPos: Pos) {}
 
     public lower(stmts: Stmt[]) {
-        this.addSourceMap({ index: 0, line: 1, col: 1 });
+        this.addClearingSourceMap();
         this.program.add(Ops.PushPtr, { label: "_start" });
         this.program.add(Ops.Jump);
         this.scoutFnHeaders(stmts);
@@ -37,6 +37,10 @@ export class Lowerer {
         this.program.add(Ops.SourceMap, index, line, col);
     }
 
+    private addClearingSourceMap() {
+        this.program.add(Ops.SourceMap, 0, 1, 1);
+    }
+
     private scoutFnHeaders(stmts: Stmt[]) {
         for (const stmt of stmts) {
             if (stmt.kind.type !== "fn") {
@@ -123,6 +127,7 @@ export class Lowerer {
         if (stmt.kind.expr) {
             this.lowerExpr(stmt.kind.expr);
         }
+        this.addClearingSourceMap();
         this.program.add(Ops.PushPtr, this.breakStack.at(-1)!);
         this.program.add(Ops.Jump);
     }
@@ -374,12 +379,14 @@ export class Lowerer {
         this.lowerExpr(expr.kind.cond);
 
         this.program.add(Ops.Not);
+        this.addClearingSourceMap();
         this.program.add(Ops.PushPtr, falseLabel);
         this.program.add(Ops.JumpIfTrue);
 
         this.addSourceMap(expr.kind.truthy.pos);
         this.lowerExpr(expr.kind.truthy);
 
+        this.addClearingSourceMap();
         this.program.add(Ops.PushPtr, doneLabel);
         this.program.add(Ops.Jump);
 
@@ -408,9 +415,11 @@ export class Lowerer {
         this.addSourceMap(expr.kind.body.pos);
         this.lowerExpr(expr.kind.body);
         this.program.add(Ops.Pop);
+        this.addClearingSourceMap();
         this.program.add(Ops.PushPtr, contineLabel);
         this.program.add(Ops.Jump);
         this.program.setLabel(breakLabel);
+        this.addSourceMap({ index: 0, line: 1, col: 1 });
         if (expr.vtype!.type === "null") {
             this.program.add(Ops.PushNull);
         }