diff --git a/packages/collections/CHANGELOG.md b/packages/collections/CHANGELOG.md
index 5bfaab445..335174dec 100644
--- a/packages/collections/CHANGELOG.md
+++ b/packages/collections/CHANGELOG.md
@@ -1,5 +1,20 @@
 # @openfn/language-collections
 
+## 0.7.0
+
+### Minor Changes
+
+- c95ccba: BREAKING: Pass state into the keygen function on `set()`. This allows
+  state to be used to calculate keys.
+
+  When calling `collections.set(collection, keygen, values)`, the keygen
+  function signature has changed from `(value, index) => key` to
+  `(value, state, index) => key`.
+
+### Patch Changes
+
+- cdb01db: Better error handling if the keygen function is invalid
+
 ## 0.6.2
 
 ### Patch Changes
diff --git a/packages/collections/package.json b/packages/collections/package.json
index dfb4d03d0..896d12e86 100644
--- a/packages/collections/package.json
+++ b/packages/collections/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@openfn/language-collections",
-  "version": "0.6.2",
+  "version": "0.7.0",
   "description": "OpenFn collections adaptor",
   "type": "module",
   "exports": {
diff --git a/packages/collections/src/collections.js b/packages/collections/src/collections.js
index 63f99e41d..79f580d57 100644
--- a/packages/collections/src/collections.js
+++ b/packages/collections/src/collections.js
@@ -173,10 +173,20 @@ export function set(name, keyGen, values) {
       // Otherwise we convert the incoming values into an array of key/value pairs
       // Note that we may need to serialize json to string
       // the hardest bit is knowing when to deserialize
-      kvPairs = dataArray.map((value, index) => ({
-        key: keyGenFn(value, index),
-        value: JSON.stringify(value),
-      }));
+      kvPairs = dataArray.map((value, index) => {
+        const key = keyGenFn(value, state, index);
+        if (typeof key !== 'string') {
+          const e = new Error('KEYGEN_ERROR');
+          e.description =
+            'The key generator function returned a non-string value which is not a valid key';
+          e.fix = `The second argument to set() is a key or key-generator function. If you pass a function, make sure the function returns a string (a key). Note that this function is NOT a state reference and does not support lazy state ($)`;
+          throw e;
+        }
+        return {
+          key,
+          value: JSON.stringify(value),
+        };
+      });
     }
 
     while (kvPairs.length) {
diff --git a/packages/collections/test/Adaptor.test.js b/packages/collections/test/Adaptor.test.js
index 6f8f16496..16fd26f7b 100644
--- a/packages/collections/test/Adaptor.test.js
+++ b/packages/collections/test/Adaptor.test.js
@@ -427,6 +427,32 @@ describe('set', () => {
     expect(err.message).to.eql('ILLEGAL_ARGUMENTS');
   });
 
+  it("should throw keygen doesn't return a string", async () => {
+    const { state } = init();
+    state.configuration = {};
+
+    let err;
+    try {
+      await collections.set(COLLECTION, () => true, { x: 1 })(state);
+    } catch (e) {
+      err = e;
+    }
+    expect(err.message).to.eql('KEYGEN_ERROR');
+  });
+
+  it('should throw keygen looks like a state reference', async () => {
+    const { state } = init();
+    state.configuration = {};
+
+    let err;
+    try {
+      await collections.set(COLLECTION, state => state, { x: 1 })(state);
+    } catch (e) {
+      err = e;
+    }
+    expect(err.message).to.eql('KEYGEN_ERROR');
+  });
+
   it('should set a single item', async () => {
     const { state } = init();
 
@@ -463,6 +489,18 @@ describe('set', () => {
     expect(result).to.eql(item);
   });
 
+  it('should pass state to the keygen function', async () => {
+    const { state } = init();
+    state.key = 'x';
+
+    const item = { id: 'x' };
+
+    await collections.set(COLLECTION, (_key, state) => state.key, item)(state);
+
+    const result = api.asJSON(COLLECTION, 'x');
+    expect(result).to.eql(item);
+  });
+
   it('should set a single array-type item with a reference', async () => {
     const { state } = init();