diff --git a/build/generate-flow-typed-style-spec.js b/build/generate-flow-typed-style-spec.js
index f483d316c91..56047f79d46 100644
--- a/build/generate-flow-typed-style-spec.js
+++ b/build/generate-flow-typed-style-spec.js
@@ -44,6 +44,8 @@ function flowType(property) {
         return `DataDrivenPropertyValueSpecification<${baseType}>`;
     } else if (property['zoom-function']) {
         return `PropertyValueSpecification<${baseType}>`;
+    } else if (property.function) {
+        return `ExpressionSpecification`;
     } else {
         return baseType;
     }
diff --git a/flow-typed/style-spec.js b/flow-typed/style-spec.js
index cb141ffd005..89c3030aafc 100644
--- a/flow-typed/style-spec.js
+++ b/flow-typed/style-spec.js
@@ -215,7 +215,7 @@ declare type SymbolLayerSpecification = {|
         "text-pitch-alignment"?: PropertyValueSpecification<"map" | "viewport" | "auto">,
         "text-rotation-alignment"?: PropertyValueSpecification<"map" | "viewport" | "auto">,
         "text-field"?: DataDrivenPropertyValueSpecification<string>,
-        "text-font"?: PropertyValueSpecification<Array<string>>,
+        "text-font"?: DataDrivenPropertyValueSpecification<Array<string>>,
         "text-size"?: DataDrivenPropertyValueSpecification<number>,
         "text-max-width"?: DataDrivenPropertyValueSpecification<number>,
         "text-line-height"?: PropertyValueSpecification<number>,
@@ -294,7 +294,7 @@ declare type HeatmapLayerSpecification = {|
         "heatmap-radius"?: PropertyValueSpecification<number>,
         "heatmap-weight"?: DataDrivenPropertyValueSpecification<number>,
         "heatmap-intensity"?: PropertyValueSpecification<number>,
-        "heatmap-color"?: PropertyValueSpecification<ColorSpecification>,
+        "heatmap-color"?: ExpressionSpecification,
         "heatmap-opacity"?: PropertyValueSpecification<number>
     |}
 |}
diff --git a/package.json b/package.json
index 25580ef9c6a..1d0e714db53 100644
--- a/package.json
+++ b/package.json
@@ -151,7 +151,7 @@
     "test-render": "node --max-old-space-size=2048 test/render.test.js",
     "test-query": "node test/query.test.js",
     "test-expressions": "node test/expression.test.js",
-    "test-flow": "flow .",
+    "test-flow": "node build/generate-flow-typed-style-spec && flow .",
     "test-flow-cov": "flow-coverage-report -i 'src/**/*.js' -t html",
     "test-cov": "nyc --require=flow-remove-types/register --reporter=text-summary --reporter=lcov --cache run-s test-unit test-expressions test-query test-render",
     "prepublish": "in-publish && run-s build-dev build-min || not-in-publish"