diff --git a/Userland/Libraries/LibJS/Bytecode/Executable.h b/Userland/Libraries/LibJS/Bytecode/Executable.h
index 6f1c3f99390..4abe68ab058 100644
--- a/Userland/Libraries/LibJS/Bytecode/Executable.h
+++ b/Userland/Libraries/LibJS/Bytecode/Executable.h
@@ -20,6 +20,7 @@ struct Executable {
     NonnullOwnPtr<StringTable> string_table;
     NonnullOwnPtr<IdentifierTable> identifier_table;
     size_t number_of_registers { 0 };
+    bool is_strict_mode { false };
 
     String const& get_string(StringTableIndex index) const { return string_table->get(index); }
     FlyString const& get_identifier(IdentifierTableIndex index) const { return identifier_table->get(index); }
diff --git a/Userland/Libraries/LibJS/Bytecode/Generator.cpp b/Userland/Libraries/LibJS/Bytecode/Generator.cpp
index 3dc17991040..76ca4ebd755 100644
--- a/Userland/Libraries/LibJS/Bytecode/Generator.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Generator.cpp
@@ -41,12 +41,24 @@ CodeGenerationErrorOr<NonnullOwnPtr<Executable>> Generator::generate(ASTNode con
             generator.emit<Bytecode::Op::Yield>(nullptr);
         }
     }
+
+    bool is_strict_mode = false;
+    if (is<Program>(node))
+        is_strict_mode = static_cast<Program const&>(node).is_strict_mode();
+    else if (is<FunctionBody>(node))
+        is_strict_mode = static_cast<FunctionBody const&>(node).in_strict_mode();
+    else if (is<FunctionDeclaration>(node))
+        is_strict_mode = static_cast<FunctionDeclaration const&>(node).is_strict_mode();
+    else if (is<FunctionExpression>(node))
+        is_strict_mode = static_cast<FunctionExpression const&>(node).is_strict_mode();
+
     return adopt_own(*new Executable {
         .name = {},
         .basic_blocks = move(generator.m_root_basic_blocks),
         .string_table = move(generator.m_string_table),
         .identifier_table = move(generator.m_identifier_table),
-        .number_of_registers = generator.m_next_register });
+        .number_of_registers = generator.m_next_register,
+        .is_strict_mode = is_strict_mode });
 }
 
 void Generator::grow(size_t additional_size)
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index 561a086b61a..dceec8c5d33 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -57,8 +57,7 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& e
         execution_context.lexical_environment = &m_realm.global_environment();
         execution_context.variable_environment = &m_realm.global_environment();
         execution_context.realm = &m_realm;
-        // FIXME: How do we know if we're in strict mode? Maybe the Bytecode::Block should know this?
-        // execution_context.is_strict_mode = ???;
+        execution_context.is_strict_mode = executable.is_strict_mode;
         vm().push_execution_context(execution_context);
         pushed_execution_context = true;
     }