diff --git a/ets2panda/lexer/scripts/keywords.yaml b/ets2panda/lexer/scripts/keywords.yaml
index 08ae6869c9a8bf14d83b52ab027894a69cad3149..76a8f6c1621c85352020dd4cb4daffbc0221df7f 100644
--- a/ets2panda/lexer/scripts/keywords.yaml
+++ b/ets2panda/lexer/scripts/keywords.yaml
@@ -297,8 +297,7 @@ keywords:
 
   - name: 'in'
     token: KEYW_IN
-    keyword: [as, js, ts]
-    keyword_like: [ets]
+    keyword: [as, js, ets, ts]
     flags: [binary]
 
   - name: 'infer'
diff --git a/ets2panda/parser/ETSparser.h b/ets2panda/parser/ETSparser.h
index 66ddcc044e8e2c478bf790a9923d043e37cef6ec..7cba7aa76a745c3e78b7bae5031094c69ac012bc 100644
--- a/ets2panda/parser/ETSparser.h
+++ b/ets2panda/parser/ETSparser.h
@@ -451,6 +451,10 @@ private:
     ir::Statement *ParseTopLevelDeclStatement(StatementParsingFlags flags);
     ir::Statement *ParseTopLevelStatement();
     void ParseTrailingBlock([[maybe_unused]] ir::CallExpression *callExpr) override;
+    bool IsInOperatorTypeSupported() const override
+    {
+        return false;
+    }
     void CheckDeclare();
 
     friend class ExternalSourceParser;
diff --git a/ets2panda/parser/expressionParser.cpp b/ets2panda/parser/expressionParser.cpp
index 6d111ce34ace4c3348ba058e12bf2ad0e88774d0..a767e196f6cdc077959d8f906d3ef3eb0f4dc878 100644
--- a/ets2panda/parser/expressionParser.cpp
+++ b/ets2panda/parser/expressionParser.cpp
@@ -1336,6 +1336,13 @@ ir::Expression *ParserImpl::ParseBinaryExpression(ir::Expression *left, Expressi
     }
 
     ir::Expression *rightExpr = ParseExpressionOrTypeAnnotation(operatorType, ExpressionParseFlags::DISALLOW_YIELD);
+
+    // NOTE(rsipka): 'in' operator is not supported but parsed the expression above for more detailed error reporting
+    if (operatorType == lexer::TokenType::KEYW_IN && !IsInOperatorTypeSupported()) {
+        LogError(diagnostic::UNSUPPORTED_IN_OPERATOR_TYPE);
+        return AllocBrokenExpression(lexer::SourceRange {left->Start(), rightExpr->End()});
+    }
+
     ir::ConditionalExpression *conditionalExpr = nullptr;
     if (rightExpr->IsConditionalExpression() && !rightExpr->IsGrouped()) {
         conditionalExpr = rightExpr->AsConditionalExpression();
diff --git a/ets2panda/parser/parserImpl.h b/ets2panda/parser/parserImpl.h
index cd39352b1d1015be72c794a3ccb5842142086e0e..748a1a4e5c1f90ed4c524b4fbed7e428db88969f 100644
--- a/ets2panda/parser/parserImpl.h
+++ b/ets2panda/parser/parserImpl.h
@@ -167,6 +167,10 @@ protected:
     virtual void ParseTrailingBlock([[maybe_unused]] ir::CallExpression *callExpr) {}
     ir::Expression *CreateBinaryAssignmentExpression(ir::Expression *assignmentExpression,
                                                      ir::Expression *lhsExpression, lexer::TokenType tokenType);
+    virtual bool IsInOperatorTypeSupported() const
+    {
+        return true;
+    }
 
     // StatementParser.Cpp
 
diff --git a/ets2panda/test/ast/compiler/ets/keyof_invalid_argument.ets b/ets2panda/test/ast/compiler/ets/keyof_invalid_argument.ets
index 5edd48126e4922f1439ab8a08ec0c2294b004999..e6d5bc837747fa835552cbabfa030552e7c11c6b 100644
--- a/ets2panda/test/ast/compiler/ets/keyof_invalid_argument.ets
+++ b/ets2panda/test/ast/compiler/ets/keyof_invalid_argument.ets
@@ -30,7 +30,7 @@ type NestedKey<T, K extends keyof T> = T[K] extends object ? keyof T[K] : never;
 /* @@? 18:33 Error TypeError: The super type of 'ObservableImpl' class is not extensible. */
 /* @@? 20:24 Error SyntaxError: Using object literals to declare types in place is not supported. Please declare types and interfaces explicitly! */
 /* @@? 20:27 Error TypeError: Indexed signatures are not allowed. Use arrays instead! */
-/* @@? 20:31 Error SyntaxError: Field type annotation expected. */
+/* @@? 20:29 Error SyntaxError: Unexpected token 'in'. */
 /* @@? 20:41 Error SyntaxError: Unexpected token '&'. */
 /* @@? 20:41 Error SyntaxError: Unexpected token, expected ',' or ')'. */
 /* @@? 20:41 Error SyntaxError: Parameter declaration should have an explicit type annotation. */
diff --git a/ets2panda/test/ast/parser/ets/circular_type_in_alias.ets b/ets2panda/test/ast/parser/ets/circular_type_in_alias.ets
index 09a0912afdb078b51efeb8e558a248d3b9c6d2fc..8a2229b5d76e5a7a5ebc064253bce13d5d2adfd6 100644
--- a/ets2panda/test/ast/parser/ets/circular_type_in_alias.ets
+++ b/ets2panda/test/ast/parser/ets/circular_type_in_alias.ets
@@ -20,7 +20,7 @@ type Loop<T, U extends Loop<T, U>> = {
 /* @@? 16:24 Error TypeError: Circular type alias reference */
 /* @@? 16:38 Error SyntaxError: Using object literals to declare types in place is not supported. Please declare types and interfaces explicitly! */
 /* @@? 17:6 Error TypeError: Indexed signatures are not allowed. Use arrays instead! */
-/* @@? 17:10 Error SyntaxError: Field type annotation expected. */
+/* @@? 17:8 Error SyntaxError: Unexpected token 'in'. */
 /* @@? 17:16 Error SyntaxError: Field type annotation expected. */
 /* @@? 17:18 Error SyntaxError: Unexpected token ']'. */
 /* @@? 17:18 Error SyntaxError: Field type annotation expected. */
diff --git a/ets2panda/test/ast/parser/ets/for_of_04.ets b/ets2panda/test/ast/parser/ets/for_of_04.ets
index 0b51c9f55cf40b74822d6ecb8756c425f4897172..3ec38b614659751a0a742497f3f8d26524ec784c 100644
--- a/ets2panda/test/ast/parser/ets/for_of_04.ets
+++ b/ets2panda/test/ast/parser/ets/for_of_04.ets
@@ -34,5 +34,4 @@ for (i in 50) {
 /* @@? 20:21 Error TypeError: Unresolved reference a */
 /* @@? 20:22 Error SyntaxError: Unexpected token ')'. */
 /* @@? 20:24 Error SyntaxError: Unexpected token '{'. */
-/* @@? 25:11 Error TypeError: Object type doesn't have proper iterator method. */
-/* @@? 25:11 Error TypeError: 'For-of' statement source expression is not of iterable type. */
+/* @@? 25:8 Error SyntaxError: 'for ... in' loop is not supported, please use regular 'for' or 'for ... of ...' loop to iterate through arrays and iterable objects. */
diff --git a/ets2panda/test/ast/parser/ets/typenode_clone_comprehensive.ets b/ets2panda/test/ast/parser/ets/typenode_clone_comprehensive.ets
index 069c51fb2f2b65c77959c4bb1af9b5001bce86c7..7a247f20567e20bf154a64019de3b27e5cdc68b0 100644
--- a/ets2panda/test/ast/parser/ets/typenode_clone_comprehensive.ets
+++ b/ets2panda/test/ast/parser/ets/typenode_clone_comprehensive.ets
@@ -89,7 +89,7 @@ declare const test3: ComplexType<'b'>;
 /* @@? 38:39 Error SyntaxError: Unexpected token ']'. */
 /* @@? 41:19 Error SyntaxError: Using object literals to declare types in place is not supported. Please declare types and interfaces explicitly! */
 /* @@? 41:22 Error TypeError: Indexed signatures are not allowed. Use arrays instead! */
-/* @@? 41:26 Error SyntaxError: Field type annotation expected. */
+/* @@? 41:24 Error SyntaxError: Unexpected token 'in'. */
 /* @@? 41:32 Error SyntaxError: Field type annotation expected. */
 /* @@? 41:43 Error SyntaxError: Unexpected token ']'. */
 /* @@? 41:43 Error SyntaxError: Field type annotation expected. */
@@ -115,7 +115,7 @@ declare const test3: ComplexType<'b'>;
 /* @@? 61:30 Error SyntaxError: Unexpected token ','. */
 /* @@? 62:13 Error SyntaxError: Using object literals to declare types in place is not supported. Please declare types and interfaces explicitly! */
 /* @@? 62:16 Error TypeError: Indexed signatures are not allowed. Use arrays instead! */
-/* @@? 62:20 Error SyntaxError: Field type annotation expected. */
+/* @@? 62:18 Error SyntaxError: Unexpected token 'in'. */
 /* @@? 62:22 Error SyntaxError: Unexpected token ']'. */
 /* @@? 62:22 Error SyntaxError: Field type annotation expected. */
 /* @@? 62:23 Error SyntaxError: Unexpected token ':'. */
diff --git a/ets2panda/test/runtime/ets/lambda_with_receiver/lambda_with_receiver_catch_outside_field.ets b/ets2panda/test/runtime/ets/lambda_with_receiver/lambda_with_receiver_catch_outside_field.ets
index 4150edd9ddc61f5c869af61c85ae92bb64e56d8c..3bb0274da4e895b57e87668252401655359c2301 100644
--- a/ets2panda/test/runtime/ets/lambda_with_receiver/lambda_with_receiver_catch_outside_field.ets
+++ b/ets2panda/test/runtime/ets/lambda_with_receiver/lambda_with_receiver_catch_outside_field.ets
@@ -15,7 +15,7 @@
 
 class C{
     out: number = 0;
-    in: number = 0;
+    input: number = 0;
     data: number = 0;
 }
 
@@ -23,7 +23,7 @@ function process1(con: (this:C)=>void){
     let c = new C();
     c.con();
     arktest.assertEQ(c.out, 1);
-    arktest.assertEQ(c.in, 2);
+    arktest.assertEQ(c.input, 2);
     arktest.assertEQ(c.data, 3);
 }
 
@@ -31,7 +31,7 @@ function process2(con: (this:C)=>void){
     let c = new C();
     c.con();
     arktest.assertEQ(c.out, 1);
-    arktest.assertEQ(c.in, 2);
+    arktest.assertEQ(c.input, 2);
     arktest.assertEQ(c.data, 3);
 }
 
@@ -41,14 +41,14 @@ function main(){
     // passed lambda as parameter.
     process1((this:C):void => {
         this.out = field_out;
-        this.in = field_in;
+        this.input = field_in;
         this.data = 3;
     })
 
     // passed lambda as trailing lambda.
     process2() {
         this.out = field_out;
-        this.in = field_in;
+        this.input = field_in;
         this.data = 3;
     }
 }
\ No newline at end of file
diff --git a/ets2panda/util/diagnostic/syntax.yaml b/ets2panda/util/diagnostic/syntax.yaml
index 2401da7d0e2450558426cb7d33c1c12f4a8a8e92..e5f3e99499fb7f52de16b5ff6e24684df6fa4587 100644
--- a/ets2panda/util/diagnostic/syntax.yaml
+++ b/ets2panda/util/diagnostic/syntax.yaml
@@ -1259,6 +1259,10 @@ syntax:
   message: "Unsupported enum type annotation. Supported enum types are: int, long or double. String is allowed for literal\
     \ types, not annotations."
 
+- name: UNSUPPORTED_IN_OPERATOR_TYPE
+  id: 58212
+  message: "The in operator is not supported in binary expression."
+
 - name: UNTERMINATED_MULTI_LINE_COMMENT
   id: 245
   message: "Unterminated multi-line comment."