diff --git a/Userland/Shell/AST.cpp b/Userland/Shell/AST.cpp
index 45dd80f8e7..f155304c6d 100644
--- a/Userland/Shell/AST.cpp
+++ b/Userland/Shell/AST.cpp
@@ -2363,7 +2363,9 @@ ErrorOr<RefPtr<Value>> MatchExpr::run(RefPtr<Shell> shell)
             return move(result).get<RefPtr<Value>>();
     }
 
-    shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, "Non-exhaustive match rules!", position());
+    // Non-exhaustive 'case' statements are valid in POSIX.
+    if (!shell || !shell->posix_mode())
+        shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, "Non-exhaustive match rules!", position());
     return make_ref_counted<AST::ListValue>({});
 }
 
diff --git a/Userland/Shell/Shell.h b/Userland/Shell/Shell.h
index 2babf1a4ce..b4e7501c88 100644
--- a/Userland/Shell/Shell.h
+++ b/Userland/Shell/Shell.h
@@ -308,6 +308,8 @@ public:
 
     void notify_child_event();
 
+    bool posix_mode() const { return m_in_posix_mode; }
+
     struct termios termios;
     struct termios default_termios;
     bool was_interrupted { false };