diff --git a/test/prism/errors/defs_endless_method.txt b/test/prism/errors/defs_endless_method.txt
new file mode 100644
index 0000000000..80db648e62
--- /dev/null
+++ b/test/prism/errors/defs_endless_method.txt
@@ -0,0 +1,12 @@
+def f=(k,v)=1
+    ^~ invalid method name; a setter method cannot be defined in an endless method definition
+
+def obj.f=(k,v)=1
+        ^~ invalid method name; a setter method cannot be defined in an endless method definition
+
+def []=(k,v)=1
+    ^~~ invalid method name; a setter method cannot be defined in an endless method definition
+
+def obj.[]=(k,v)=1
+        ^~~ invalid method name; a setter method cannot be defined in an endless method definition
+