diff --git a/README.md b/README.md
index afb7d2b..bfea89e 100644
--- a/README.md
+++ b/README.md
@@ -208,5 +208,6 @@ fn main() {
 
 ## Feature Flags
 - `chrono` - implements `JsonSchema` for all [Chrono](https://github.com/chronotope/chrono) types which are serializable by Serde.
+- `indexmap` - implements `JsonSchema` on `IndexMap` and `IndexSet` from [indexmap](https://github.com/bluss/indexmap).
 - `impl_json_schema` - implements `JsonSchema` for Schemars types themselves
 
diff --git a/docs/4-features.md b/docs/4-features.md
index 93bb7b9..6e810a0 100644
--- a/docs/4-features.md
+++ b/docs/4-features.md
@@ -23,4 +23,8 @@ Implements `JsonSchema` on Schemars types themselves.
 
 Implements `JsonSchema` on all [Chrono](https://github.com/chronotope/chrono) types which are serializable by Serde.
 
+### indexmap
+
+Implements `JsonSchema` on `IndexMap` and `IndexSet` from [indexmap](https://github.com/bluss/indexmap).
+
 </div>
diff --git a/schemars/Cargo.toml b/schemars/Cargo.toml
index 53b0f70..c91a8a9 100644
--- a/schemars/Cargo.toml
+++ b/schemars/Cargo.toml
@@ -16,7 +16,9 @@ build = "build.rs"
 schemars_derive = { version = "=0.6.3", path = "../schemars_derive" }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+
 chrono = { version = "0.4", default-features = false, optional = true }
+indexmap = { version = "1.2", optional = true }
 
 [dev-dependencies]
 pretty_assertions = "0.6.1"
@@ -30,6 +32,10 @@ derive_json_schema = ["impl_json_schema"]
 name = "chrono"
 required-features = ["chrono"]
 
+[[test]]
+name = "indexmap"
+required-features = ["indexmap"]
+
 [[test]]
 name = "schema_for_schema"
 required-features = ["impl_json_schema"]
diff --git a/schemars/src/json_schema_impls/indexmap.rs b/schemars/src/json_schema_impls/indexmap.rs
new file mode 100644
index 0000000..3bd3e54
--- /dev/null
+++ b/schemars/src/json_schema_impls/indexmap.rs
@@ -0,0 +1,8 @@
+use crate::gen::SchemaGenerator;
+use crate::schema::*;
+use crate::JsonSchema;
+use indexmap::{IndexMap, IndexSet};
+use std::collections::{HashMap, HashSet};
+
+forward_impl!((<K, V: JsonSchema, H> JsonSchema for IndexMap<K, V, H>) => HashMap<K, V, H>);
+forward_impl!((<T: JsonSchema, H> JsonSchema for IndexSet<T, H>) => HashSet<T, H>);
diff --git a/schemars/src/json_schema_impls/maps.rs b/schemars/src/json_schema_impls/maps.rs
index c109b00..73f3313 100644
--- a/schemars/src/json_schema_impls/maps.rs
+++ b/schemars/src/json_schema_impls/maps.rs
@@ -6,7 +6,6 @@ macro_rules! map_impl {
     ($($desc:tt)+) => {
         impl $($desc)+
         where
-            K: Into<String>,
             V: JsonSchema,
         {
             no_ref_schema!();
diff --git a/schemars/src/json_schema_impls/mod.rs b/schemars/src/json_schema_impls/mod.rs
index 8db5fd6..389719c 100644
--- a/schemars/src/json_schema_impls/mod.rs
+++ b/schemars/src/json_schema_impls/mod.rs
@@ -36,6 +36,8 @@ mod array;
 mod atomic;
 #[cfg(feature = "chrono")]
 mod chrono;
+#[cfg(feature = "indexmap")]
+mod indexmap;
 mod core;
 mod ffi;
 mod maps;
diff --git a/schemars/tests/expected/indexmap.json b/schemars/tests/expected/indexmap.json
new file mode 100644
index 0000000..e9d4df4
--- /dev/null
+++ b/schemars/tests/expected/indexmap.json
@@ -0,0 +1,24 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "IndexMapTypes",
+  "type": "object",
+  "required": [
+    "map",
+    "set"
+  ],
+  "properties": {
+    "map": {
+      "type": "object",
+      "additionalProperties": {
+        "type": "boolean"
+      }
+    },
+    "set": {
+      "type": "array",
+      "items": {
+        "type": "integer",
+        "format": "int"
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/schemars/tests/indexmap.rs b/schemars/tests/indexmap.rs
new file mode 100644
index 0000000..1f0c70f
--- /dev/null
+++ b/schemars/tests/indexmap.rs
@@ -0,0 +1,15 @@
+mod util;
+use indexmap::{IndexMap, IndexSet};
+use schemars::JsonSchema;
+use util::*;
+
+#[derive(Debug, JsonSchema)]
+struct IndexMapTypes {
+    map: IndexMap<i32, bool>,
+    set: IndexSet<isize>,
+}
+
+#[test]
+fn chrono_types() -> TestResult {
+    test_default_generated_schema::<IndexMapTypes>("indexmap")
+}