diff --git a/dist/examples/examples.js b/dist/examples/examples.js
index 50e38d4..f7f8a8c 100644
--- a/dist/examples/examples.js
+++ b/dist/examples/examples.js
@@ -1005,8 +1005,8 @@ if a=1 then a=2 else a=1
 ''input ;"para noCRLF";a$,b
 ''input#2,;"para noCRLF";a$,b
 ''input#stream,;"string";a$,b
-''a=instr("key","ey")
-''a=instr(s$,find$)
+a=instr("key","ey")
+a=instr(s$,find$)
 ''a=instr(start,s$,find$)
 a=int(-2.3)
 a=int(b+2.3)
diff --git a/src/Core.ts b/src/Core.ts
index b701c59..9432b59 100644
--- a/src/Core.ts
+++ b/src/Core.ts
@@ -96,7 +96,7 @@ export class Core implements ICore {
 		this.vm.setOutput("");
 
 		if (compiledScript.startsWith("ERROR")) {
-			return "ERROR" + "\n";
+			return "ERROR";
 		}
 
 		let output: string;
@@ -127,6 +127,6 @@ export class Core implements ICore {
 				output += "unknown";
 			}
 		}
-		return output + "\n";
+		return output;
 	}
 }
diff --git a/src/Semantics.ts b/src/Semantics.ts
index 65c5b51..b2eafd5 100644
--- a/src/Semantics.ts
+++ b/src/Semantics.ts
@@ -124,7 +124,6 @@ function getSemantics(semanticsHelper: SemanticsHelper) {
 
 			const commentStr = comment.sourceString ? `; //${comment.sourceString.substring(1)}` : "";
 			const semi = lineStr === "" || lineStr.endsWith("{") || lineStr.endsWith("}") || lineStr.startsWith("//") || commentStr ? "" : ";";
-			//lineIndex += 1;
 
 			const indentStr = semanticsHelper.getIndentStr();
 			semanticsHelper.applyNextIndent();
@@ -192,7 +191,6 @@ function getSemantics(semanticsHelper: SemanticsHelper) {
 			}
 
 			dataList.push(argList.join(", "));
-			//defineData(argList);
 			return "";
 		},
 
@@ -311,6 +309,10 @@ function getSemantics(semanticsHelper: SemanticsHelper) {
 			return `${ident} = await _input(${msgStr}${isNumStr})`;
 		},
 
+		Instr(_instrLit: Node, _open: Node, e1: Node, _comma: Node, e2: Node, _close: Node) { // eslint-disable-line @typescript-eslint/no-unused-vars
+			return `((${e1.eval()}).indexOf(${e2.eval()}) + 1)`;
+		},
+
 		Int(_intLit: Node, _open: Node, e: Node, _close: Node) { // eslint-disable-line @typescript-eslint/no-unused-vars
 			return `Math.floor(${e.eval()})`;
 		},
@@ -734,7 +736,7 @@ export class Semantics {
 		return name;
 	}
 
-	private deleteAllItems(items: Record<string, any>) {
+	private static deleteAllItems(items: Record<string, any>) {
 		for (const name in items) { // eslint-disable-line guard-for-in
 			delete items[name];
 		}
@@ -761,11 +763,12 @@ export class Semantics {
 		this.lineIndex = 0;
 		this.indent = 0;
 		this.indentAdd = 0;
-		this.deleteAllItems(this.variables);
+		Semantics.deleteAllItems(this.variables);
 		this.definedLabels.length = 0;
-		this.deleteAllItems(this.gosubLabels);
+		Semantics.deleteAllItems(this.gosubLabels);
 		this.dataList.length = 0;
-		this.deleteAllItems(this.restoreMap);
+		Semantics.deleteAllItems(this.restoreMap);
+		Semantics.deleteAllItems(this.instrMap);
 	}
 
 	public getSemantics() {
diff --git a/src/Ui.ts b/src/Ui.ts
index ccf7d47..a203b4a 100644
--- a/src/Ui.ts
+++ b/src/Ui.ts
@@ -49,7 +49,7 @@ export class Ui implements IUi {
 
 		const output = await this.core.executeScript(compiledScript);
 
-		this.setOutputText(this.getOutputText() + output);
+		this.setOutputText(this.getOutputText() + output + (output.endsWith("\n") ? "" : "\n"));
 	}
 
 	private oncompiledTextChange(_event: Event) { // eslint-disable-line @typescript-eslint/no-unused-vars
diff --git a/src/arithmetic.ts b/src/arithmetic.ts
index fc5d88a..02c84c6 100644
--- a/src/arithmetic.ts
+++ b/src/arithmetic.ts
@@ -108,6 +108,9 @@ export const arithmetic = {
     Input
       = caseInsensitive<"input"> (string (";" | ","))? AnyIdent  // or NonemptyListOf?
 
+    Instr
+      = caseInsensitive<"instr"> "(" StrExp "," StrExp ")"
+
     Int
       = caseInsensitive<"int"> "(" NumExp ")"
 
@@ -320,6 +323,7 @@ export const arithmetic = {
       | Cos
       | Exp
       | Fix
+      | Instr
       | Int
       | Len
       | Log
diff --git a/src/main.ts b/src/main.ts
index 919281c..865e8ed 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -93,11 +93,11 @@ function start(input: string) {
 	if (input !== "") {
 		const compiledScript = core.compileScript(input);
 
-		console.log("INFO: Compiled:\n" + compiledScript + "\n");
+		console.log("INFO: Compiled:\n" + compiledScript + "\n---");
 
 		return keepRunning(async () => {
 			const output = await core.executeScript(compiledScript);
-			console.log(output);
+			console.log(output.replace(/\n$/, ""));
 		}, 5000);
 	} else {
 		console.log("No input");