diff --git a/src/EscapeSequenceParser.test.ts b/src/EscapeSequenceParser.test.ts
index fc9bbe7a..01e018ef 100644
--- a/src/EscapeSequenceParser.test.ts
+++ b/src/EscapeSequenceParser.test.ts
@@ -110,18 +110,18 @@ let state: any;
 // parser with Uint8Array based transition table
 let parserUint = new TestEscapeSequenceParser(VT500_TRANSITION_TABLE);
 parserUint.setPrintHandler(testTerminal.print.bind(testTerminal));
-parserUint.setCsiHandlerFallback((...params: any[]) => {
-  testTerminal.actionCSI(params[0], params[1], String.fromCharCode(params[2]));
+parserUint.setCsiHandlerFallback((collect: string, params: number[], flag: number) => {
+  testTerminal.actionCSI(collect, params, String.fromCharCode(flag));
 });
-parserUint.setEscHandlerFallback((...params: any[]) => {
-  testTerminal.actionESC(params[0], String.fromCharCode(params[1]));
+parserUint.setEscHandlerFallback((collect: string, flag: number) => {
+  testTerminal.actionESC(collect, String.fromCharCode(flag));
 });
-parserUint.setExecuteHandlerFallback((...params: any[]) => {
-  testTerminal.actionExecute(String.fromCharCode(params[0]));
+parserUint.setExecuteHandlerFallback((code: number) => {
+  testTerminal.actionExecute(String.fromCharCode(code));
 });
-parserUint.setOscHandlerFallback((...params: any[]) => {
-  if (params[0] === -1) testTerminal.actionOSC(params[1]);  // handle error condition silently
-  else testTerminal.actionOSC(params[0] + ';' + params[1]);
+parserUint.setOscHandlerFallback((identifier: number, data: string) => {
+  if (identifier === -1) testTerminal.actionOSC(data);  // handle error condition silently
+  else testTerminal.actionOSC('' + identifier + ';' + data);
 });
 parserUint.setDcsHandlerFallback(new DcsTest());
 
@@ -135,18 +135,18 @@ for (let i = 0; i < VT500_TRANSITION_TABLE.table.length; ++i) {
 // parser with array based transition table
 let parserArray = new TestEscapeSequenceParser(VT500_TRANSITION_TABLE_ARRAY);
 parserArray.setPrintHandler(testTerminal.print.bind(testTerminal));
-parserArray.setCsiHandlerFallback((...params: any[]) => {
-  testTerminal.actionCSI(params[0], params[1], String.fromCharCode(params[2]));
+parserArray.setCsiHandlerFallback((collect: string, params: number[], flag: number) => {
+  testTerminal.actionCSI(collect, params, String.fromCharCode(flag));
 });
-parserArray.setEscHandlerFallback((...params: any[]) => {
-  testTerminal.actionESC(params[0], String.fromCharCode(params[1]));
+parserArray.setEscHandlerFallback((collect: string, flag: number) => {
+  testTerminal.actionESC(collect, String.fromCharCode(flag));
 });
-parserArray.setExecuteHandlerFallback((...params: any[]) => {
-  testTerminal.actionExecute(String.fromCharCode(params[0]));
+parserArray.setExecuteHandlerFallback((code: number) => {
+  testTerminal.actionExecute(String.fromCharCode(code));
 });
-parserArray.setOscHandlerFallback((...params: any[]) => {
-  if (params[0] === -1) testTerminal.actionOSC(params[1]);  // handle error condition silently
-  else testTerminal.actionOSC(params[0] + ';' + params[1]);
+parserArray.setOscHandlerFallback((identifier: number, data: string) => {
+  if (identifier === -1) testTerminal.actionOSC(data);  // handle error condition silently
+  else testTerminal.actionOSC('' + identifier + ';' + data);
 });
 parserArray.setDcsHandlerFallback(new DcsTest());
 
diff --git a/src/EscapeSequenceParser.ts b/src/EscapeSequenceParser.ts
index 5aabc251..207c32e9 100644
--- a/src/EscapeSequenceParser.ts
+++ b/src/EscapeSequenceParser.ts
@@ -227,10 +227,10 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
 
   // fallback handlers
   protected _printHandlerFb: (data: string, start: number, end: number) => void;
-  protected _executeHandlerFb: (...params: any[]) => void;
-  protected _csiHandlerFb: (...params: any[]) => void;
-  protected _escHandlerFb: (...params: any[]) => void;
-  protected _oscHandlerFb: (...params: any[]) => void;
+  protected _executeHandlerFb: (code: number) => void;
+  protected _csiHandlerFb: (collect: string, params: number[], flag: number) => void;
+  protected _escHandlerFb: (collect: string, flag: number) => void;
+  protected _oscHandlerFb: (identifier: number, data: string) => void;
   protected _dcsHandlerFb: IDcsHandler;
   protected _errorHandlerFb: (state: IParsingState) => IParsingState;
 
@@ -243,10 +243,10 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
 
     // set default fallback handlers and handler lookup containers
     this._printHandlerFb = (data, start, end): void => { };
-    this._executeHandlerFb = (...params: any[]): void => { };
-    this._csiHandlerFb = (...params: any[]): void => { };
-    this._escHandlerFb = (...params: any[]): void => { };
-    this._oscHandlerFb = (...params: any[]): void => { };
+    this._executeHandlerFb = (code: number): void => { };
+    this._csiHandlerFb = (collect: string, params: number[], flag: number): void => { };
+    this._escHandlerFb = (collect: string, flag: number): void => { };
+    this._oscHandlerFb = (identifier: number, data: string): void => { };
     this._dcsHandlerFb = new DcsDummy();
     this._errorHandlerFb = (state: IParsingState): IParsingState => state;
     this._printHandler = this._printHandlerFb;
@@ -272,7 +272,7 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
   clearExecuteHandler(flag: string): void {
     if (this._executeHandlers[flag.charCodeAt(0)]) delete this._executeHandlers[flag.charCodeAt(0)];
   }
-  setExecuteHandlerFallback(callback: (...params: any[]) => void): void {
+  setExecuteHandlerFallback(callback: (code: number) => void): void {
     this._executeHandlerFb = callback;
   }
 
@@ -282,7 +282,7 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
   clearCsiHandler(flag: string): void {
     if (this._csiHandlers[flag.charCodeAt(0)]) delete this._csiHandlers[flag.charCodeAt(0)];
   }
-  setCsiHandlerFallback(callback: (...params: any[]) => void): void {
+  setCsiHandlerFallback(callback: (collect: string, params: number[], flag: number) => void): void {
     this._csiHandlerFb = callback;
   }
 
@@ -292,7 +292,7 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
   clearEscHandler(collectAndFlag: string): void {
     if (this._escHandlers[collectAndFlag]) delete this._escHandlers[collectAndFlag];
   }
-  setEscHandlerFallback(callback: (...params: any[]) => void): void {
+  setEscHandlerFallback(callback: (collect: string, flag: number) => void): void {
     this._escHandlerFb = callback;
   }
 
@@ -302,7 +302,7 @@ export class EscapeSequenceParser implements IEscapeSequenceParser {
   clearOscHandler(ident: number): void {
     if (this._oscHandlers[ident]) delete this._oscHandlers[ident];
   }
-  setOscHandlerFallback(callback: (...params: any[]) => void): void {
+  setOscHandlerFallback(callback: (identifier: number, data: string) => void): void {
     this._oscHandlerFb = callback;
   }
 
diff --git a/src/InputHandler.ts b/src/InputHandler.ts
index b8f68fc1..397ec984 100644
--- a/src/InputHandler.ts
+++ b/src/InputHandler.ts
@@ -119,17 +119,17 @@ export class InputHandler implements IInputHandler {
     /**
      * custom fallback handlers
      */
-    this._parser.setCsiHandlerFallback((...params: any[]) => {
-      this._terminal.error('Unknown CSI code: ', params);
+    this._parser.setCsiHandlerFallback((collect: string, params: number[], flag: number) => {
+      this._terminal.error('Unknown CSI code: ', collect, params, String.fromCharCode(flag));
     });
-    this._parser.setEscHandlerFallback((...params: any[]) => {
-      this._terminal.error('Unknown ESC code: ', params);
+    this._parser.setEscHandlerFallback((collect: string, flag: number) => {
+      this._terminal.error('Unknown ESC code: ', collect, String.fromCharCode(flag));
     });
-    this._parser.setExecuteHandlerFallback((...params: any[]) => {
-      this._terminal.error('Unknown EXECUTE code: ', params);
+    this._parser.setExecuteHandlerFallback((code: number) => {
+      this._terminal.error('Unknown EXECUTE code: ', code);
     });
-    this._parser.setOscHandlerFallback((...params: any[]) => {
-      this._terminal.error('Unknown OSC code: ', params);
+    this._parser.setOscHandlerFallback((identifier: number, data: string) => {
+      this._terminal.error('Unknown OSC code: ', identifier, data);
     });
 
     /**
diff --git a/src/Types.ts b/src/Types.ts
index 60f923d7..52812e3d 100644
--- a/src/Types.ts
+++ b/src/Types.ts
@@ -483,19 +483,19 @@ export interface IEscapeSequenceParser {
 
   setExecuteHandler(flag: string, callback: () => void): void;
   clearExecuteHandler(flag: string): void;
-  setExecuteHandlerFallback(callback: (...params: any[]) => void): void;
+  setExecuteHandlerFallback(callback: (code: number) => void): void;
 
   setCsiHandler(flag: string, callback: (params: number[], collect: string) => void): void;
   clearCsiHandler(flag: string): void;
-  setCsiHandlerFallback(callback: (...params: any[]) => void): void;
+  setCsiHandlerFallback(callback: (collect: string, params: number[], flag: number) => void): void;
 
   setEscHandler(collectAndFlag: string, callback: () => void): void;
   clearEscHandler(collectAndFlag: string): void;
-  setEscHandlerFallback(callback: (...params: any[]) => void): void;
+  setEscHandlerFallback(callback: (collect: string, flag: number) => void): void;
 
   setOscHandler(ident: number, callback: (data: string) => void): void;
   clearOscHandler(ident: number): void;
-  setOscHandlerFallback(callback: (...params: any[]) => void): void;
+  setOscHandlerFallback(callback: (identifier: number, data: string) => void): void;
 
   setDcsHandler(collectAndFlag: string, handler: IDcsHandler): void;
   clearDcsHandler(collectAndFlag: string): void;