diff --git a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.h b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.h
index 817eb17432..fcc77f569d 100644
--- a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.h
+++ b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.h
@@ -242,7 +242,8 @@ protected:
 #define ENUMERATE_UNARY_OPERATORS(F) \
     F(Invalid)                       \
     F(AssertCompletion)              \
-    F(Minus)
+    F(Minus)                         \
+    F(ReturnIfAbrubt)
 
 #define ENUMERATE_BINARY_OPERATORS(F) \
     F(Invalid)                        \
diff --git a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Lexer.cpp b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Lexer.cpp
index 0025705fee..b694488bad 100644
--- a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Lexer.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Lexer.cpp
@@ -71,6 +71,7 @@ void tokenize_string(SpecificationParsingContext& ctx, XML::Node const* node, St
         { ")"sv, TokenType::ParenClose },
         { "("sv, TokenType::ParenOpen },
         { "+"sv, TokenType::Plus },
+        { "?"sv, TokenType::QuestionMark },
     };
 
     LineTrackingLexer lexer(view, node->offset);
diff --git a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Token.h b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Token.h
index fb2aa2a34d..79bd62483c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Token.h
+++ b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Parser/Token.h
@@ -44,6 +44,7 @@ constexpr i32 closing_bracket_precedence = 18;
     F(ParenClose, 18, Invalid, Invalid, ParenOpen, "')'")                            \
     F(ParenOpen, -1, Invalid, Invalid, ParenClose, "'('")                            \
     F(Plus, 6, Invalid, Plus, Invalid, "plus")                                       \
+    F(QuestionMark, 3, ReturnIfAbrubt, Invalid, Invalid, "question mark")            \
     F(SectionNumber, -1, Invalid, Invalid, Invalid, "section number")                \
     F(String, -1, Invalid, Invalid, Invalid, "string literal")                       \
     F(Superscript, 4, Invalid, Power, Invalid, "subscript")                          \
diff --git a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml
index 2c8c1d7c0c..7fce954d55 100644
--- a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml
+++ b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml
@@ -33,4 +33,12 @@
          </ol>
       </emu-alg>
    </emu-clause>
+   <emu-clause id="3" aoid="TestReturnIfAbrupt">
+      <h1><span class="secnum">3</span> TestReturnIfAbrupt ( <var>a</var> )</h1>
+      <emu-alg>
+         <ol>
+            <li>Return ? <emu-xref><a>WellKnownConstants</a></emu-xref>(<var>a</var>).</li>
+         </ol>
+      </emu-alg>
+   </emu-clause>
 </specification>
diff --git a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml.expectation b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml.expectation
index f85856a9cd..3583354b24 100644
--- a/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml.expectation
+++ b/Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Tests/spec-parsing.xml.expectation
@@ -46,3 +46,11 @@ TreeList
       ReturnNode
         WellKnownNode False
 
+TestReturnIfAbrupt(a):
+TreeList
+  ReturnNode
+    UnaryOperation ReturnIfAbrubt
+      FunctionCall
+        Func "WellKnownConstants"
+        Var a
+