diff --git a/src/style-spec/validate/validate_function.js b/src/style-spec/validate/validate_function.js
index b7a9bf3f616..a63ce3a2443 100644
--- a/src/style-spec/validate/validate_function.js
+++ b/src/style-spec/validate/validate_function.js
@@ -12,7 +12,7 @@ module.exports = function validateFunction(options) {
     const functionValueSpec = options.valueSpec;
     const functionType = unbundle(options.value.type);
     let stopKeyType;
-    const stopDomainValues = {};
+    let stopDomainValues = {};
     let previousStopDomainValue;
     let previousStopDomainZoom;
 
@@ -114,6 +114,7 @@ module.exports = function validateFunction(options) {
             if (unbundle(value[0].zoom) !== previousStopDomainZoom) {
                 previousStopDomainZoom = unbundle(value[0].zoom);
                 previousStopDomainValue = undefined;
+                stopDomainValues = {};
             }
             errors = errors.concat(validateObject({
                 key: `${key}[0]`,
diff --git a/test/unit/style-spec/fixture/functions.input.json b/test/unit/style-spec/fixture/functions.input.json
index 5fded8e46c8..808de749063 100644
--- a/test/unit/style-spec/fixture/functions.input.json
+++ b/test/unit/style-spec/fixture/functions.input.json
@@ -724,6 +724,83 @@
         }
       }
     },
+    {
+      "id": "invalid categorical zoom-and-property function - repeated stop",
+      "type": "fill",
+      "source": "source",
+      "source-layer": "layer",
+      "paint": {
+        "fill-opacity": {
+          "property": "mapbox",
+          "type": "categorical",
+          "stops": [
+            [
+              {
+                "zoom": 0,
+                "value": "0"
+              },
+              0
+            ],
+            [
+              {
+                "zoom": 0,
+                "value": "1"
+              },
+              0
+            ],
+            [
+              {
+                "zoom": 0,
+                "value": "0"
+              },
+              0
+            ]
+          ]
+        }
+      }
+    },
+    {
+      "id": "valid categorical zoom-and-property function",
+      "type": "fill",
+      "source": "source",
+      "source-layer": "layer",
+      "paint": {
+        "fill-opacity": {
+          "property": "mapbox",
+          "type": "categorical",
+          "stops": [
+            [
+              {
+                "zoom": 0,
+                "value": "0"
+              },
+              0
+            ],
+            [
+              {
+                "zoom": 0,
+                "value": "1"
+              },
+              1
+            ],
+            [
+              {
+                "zoom": 1,
+                "value": "0"
+              },
+              0
+            ],
+            [
+              {
+                "zoom": 1,
+                "value": "1"
+              },
+              1
+            ]
+          ]
+        }
+      }
+    },
     {
       "id": "valid default",
       "type": "fill",
diff --git a/test/unit/style-spec/fixture/functions.output.json b/test/unit/style-spec/fixture/functions.output.json
index 6526a72217e..26f78c5e6ef 100644
--- a/test/unit/style-spec/fixture/functions.output.json
+++ b/test/unit/style-spec/fixture/functions.output.json
@@ -79,13 +79,13 @@
     "message": "layers[19].paint.fill-color: \"property\" property is required",
     "line": 354
   },
-  {
-    "message": "layers[32].paint.fill-color.stops[0][0]: stop domain value must be a number, string, or boolean"
-  },
   {
     "message": "layers[22].paint.fill-color: missing required property \"property\"",
     "line": 401
   },
+  {
+    "message": "layers[32].paint.fill-color.stops[0][0]: stop domain value must be a number, string, or boolean"
+  },
   {
     "message": "layers[23].paint.fill-color.stops: identity function may not have a \"stops\" property",
     "line": 415
@@ -147,11 +147,15 @@
     "line": 718
   },
   {
-    "message": "layers[40].paint.fill-opacity.default: number expected, string found",
-    "line": 749
+    "message": "layers[39].paint.fill-opacity.stops[2][0].value: stop domain values must be unique",
+    "line": 754
+  },
+  {
+    "message": "layers[42].paint.fill-opacity.default: number expected, string found",
+    "line": 826
   },
   {
-    "message": "layers[41].paint.fill-color.default: color expected, \"invalid\" found",
-    "line": 762
+    "message": "layers[43].paint.fill-color.default: color expected, \"invalid\" found",
+    "line": 839
   }
 ]
\ No newline at end of file