diff --git a/prism_compile.c b/prism_compile.c
index 0e65d16d2e..e8eab6ed35 100644
--- a/prism_compile.c
+++ b/prism_compile.c
@@ -2539,6 +2539,7 @@ pm_compile_defined_expr0(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *co
       case PM_CASE_NODE:
       case PM_CASE_MATCH_NODE:
       case PM_CLASS_NODE:
+      case PM_DEF_NODE:
       case PM_DEFINED_NODE:
       case PM_FLOAT_NODE:
       case PM_HASH_NODE:
diff --git a/test/ruby/test_compile_prism.rb b/test/ruby/test_compile_prism.rb
index d3ee027ef4..98083c4368 100644
--- a/test/ruby/test_compile_prism.rb
+++ b/test/ruby/test_compile_prism.rb
@@ -252,6 +252,7 @@ module Prism
       assert_prism_eval("defined?(case :a; when :a; 1; else; 2; end)")
       assert_prism_eval("defined?(case [1, 2, 3]; in [1, 2, 3]; 4; end)")
       assert_prism_eval("defined?(class PrismClassA; end)")
+      assert_prism_eval("defined?(def prism_test_def_node; end)")
     end
 
     def test_GlobalVariableReadNode