diff --git a/ext/json/ext/parser/parser.c b/ext/json/ext/parser/parser.c
index b7de60ddf..8b860c410 100644
--- a/ext/json/ext/parser/parser.c
+++ b/ext/json/ext/parser/parser.c
@@ -2363,9 +2363,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
 	char buf[4];
 
 	if (bufferSize > MAX_STACK_BUFFER_SIZE) {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+		bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
+# else
 		bufferStart = buffer = ALLOC_N(char, bufferSize);
+# endif
 	} else {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+		bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
+# else
 		bufferStart = buffer = ALLOCA_N(char, bufferSize);
+# endif
 	}
 
 	while (pe < stringEnd) {
diff --git a/ext/json/ext/parser/parser.rl b/ext/json/ext/parser/parser.rl
index 15e6b929f..2dee80ee3 100644
--- a/ext/json/ext/parser/parser.rl
+++ b/ext/json/ext/parser/parser.rl
@@ -462,9 +462,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
     char buf[4];
 
     if (bufferSize > MAX_STACK_BUFFER_SIZE) {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+      bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
+# else
       bufferStart = buffer = ALLOC_N(char, bufferSize);
+# endif
     } else {
+# ifdef HAVE_RB_ENC_INTERNED_STR
+      bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
+# else
       bufferStart = buffer = ALLOCA_N(char, bufferSize);
+# endif
     }
 
     while (pe < stringEnd) {
diff --git a/tests/json_parser_test.rb b/tests/json_parser_test.rb
index dce693e54..00b254fc6 100644
--- a/tests/json_parser_test.rb
+++ b/tests/json_parser_test.rb
@@ -84,6 +84,7 @@ def test_parse_simple_objects
     assert_equal({ "a" => 23 }, parse('  { "a"  : 23  } '))
     assert_equal({ "a" => 0.23 }, parse(' { "a"  :  0.23 }  '))
     assert_equal({ "a" => 0.23 }, parse('  {  "a"  :  0.23  }  '))
+    assert_equal({ "" => 123 }, parse('{"":123}'))
   end
 
   def test_parse_numbers