diff --git a/ext/objspace/objspace_dump.c b/ext/objspace/objspace_dump.c
index b570acbd95..18e052f210 100644
--- a/ext/objspace/objspace_dump.c
+++ b/ext/objspace/objspace_dump.c
@@ -313,6 +313,16 @@ reachable_object_i(VALUE ref, void *data)
     dc->cur_obj_references++;
 }
 
+bool
+dump_string_ascii_only(const char *str, long size) {
+    for (long i = 0; i < size; i++) {
+        if (str[i] & 0x80) {
+            return false;
+        }
+    }
+    return true;
+}
+
 static void
 dump_append_string_content(struct dump_config *dc, VALUE obj)
 {
@@ -323,9 +333,17 @@ dump_append_string_content(struct dump_config *dc, VALUE obj)
         dump_append_sizet(dc, rb_str_capacity(obj));
     }
 
-    if (is_ascii_string(obj)) {
-        dump_append(dc, ", \"value\":");
-        dump_append_string_value(dc, obj);
+    if (RSTRING_LEN(obj) && rb_enc_asciicompat(rb_enc_from_index(ENCODING_GET(obj)))) {
+        int cr = ENC_CODERANGE(obj);
+        if (cr == RUBY_ENC_CODERANGE_UNKNOWN) {
+            if (dump_string_ascii_only(RSTRING_PTR(obj), RSTRING_LEN(obj))) {
+                cr = RUBY_ENC_CODERANGE_7BIT;
+            }
+        }
+        if (cr == RUBY_ENC_CODERANGE_7BIT) {
+            dump_append(dc, ", \"value\":");
+            dump_append_string_value(dc, obj);
+        }
     }
 }
 
@@ -389,8 +407,6 @@ dump_object(VALUE obj, struct dump_config *dc)
       case T_STRING:
         if (STR_EMBED_P(obj))
             dump_append(dc, ", \"embedded\":true");
-        if (is_broken_string(obj))
-            dump_append(dc, ", \"broken\":true");
         if (FL_TEST(obj, RSTRING_FSTR))
             dump_append(dc, ", \"fstring\":true");
         if (STR_SHARED_P(obj))
@@ -403,6 +419,27 @@ dump_object(VALUE obj, struct dump_config *dc)
             dump_append(dc, rb_enc_name(rb_enc_from_index(ENCODING_GET(obj))));
             dump_append(dc, "\"");
         }
+
+        dump_append(dc, ", \"coderange\":\"");
+        switch (RB_ENC_CODERANGE(obj)) {
+          case RUBY_ENC_CODERANGE_UNKNOWN:
+            dump_append(dc, "unknown");
+            break;
+          case RUBY_ENC_CODERANGE_7BIT:
+            dump_append(dc, "7bit");
+            break;
+          case RUBY_ENC_CODERANGE_VALID:
+            dump_append(dc, "valid");
+            break;
+          case RUBY_ENC_CODERANGE_BROKEN:
+            dump_append(dc, "broken");
+            break;
+        }
+        dump_append(dc, "\"");
+
+        if (RB_ENC_CODERANGE(obj) == RUBY_ENC_CODERANGE_BROKEN)
+            dump_append(dc, ", \"broken\":true");
+
         break;
 
       case T_HASH:
diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
index ed9c998597..1392447e4f 100644
--- a/test/objspace/test_objspace.rb
+++ b/test/objspace/test_objspace.rb
@@ -486,6 +486,16 @@ class TestObjSpace < Test::Unit::TestCase
     end
   end
 
+  def test_dump_string_coderange
+    assert_includes ObjectSpace.dump("TEST STRING"), '"coderange":"7bit"'
+    unknown = "TEST STRING".dup.force_encoding(Encoding::BINARY)
+    2.times do # ensure that dumping the string doesn't mutate it
+      assert_includes ObjectSpace.dump(unknown), '"coderange":"unknown"'
+    end
+    assert_includes ObjectSpace.dump("Fée"), '"coderange":"valid"'
+    assert_includes ObjectSpace.dump("\xFF"), '"coderange":"broken"'
+  end
+
   def test_dump_escapes_method_name
     method_name = "foo\"bar"
     klass = Class.new do