diff --git a/dawn.json b/dawn.json
index 0e338a7772..c4de76587b 100644
--- a/dawn.json
+++ b/dawn.json
@@ -893,7 +893,7 @@
         "members": [
             {"name": "layout", "type": "pipeline layout"},
             {"name": "vertex stage", "type": "pipeline stage descriptor", "annotation": "const*"},
-            {"name": "fragment stage", "type": "pipeline stage descriptor", "annotation": "const*"},
+            {"name": "fragment stage", "type": "pipeline stage descriptor", "annotation": "const*", "optional": true},
             {"name": "vertex input", "type": "vertex input descriptor", "annotation": "const*"},
             {"name": "primitive topology", "type": "primitive topology"},
             {"name": "rasterization state", "type": "rasterization state descriptor", "annotation": "const*", "optional": true},
diff --git a/src/dawn_native/RenderPipeline.cpp b/src/dawn_native/RenderPipeline.cpp
index db022c7d57..a9fd5d707d 100644
--- a/src/dawn_native/RenderPipeline.cpp
+++ b/src/dawn_native/RenderPipeline.cpp
@@ -271,6 +271,11 @@ namespace dawn_native {
             return DAWN_VALIDATION_ERROR("Input state must not be null");
         }
 
+        // TODO(crbug.com/dawn/136): Support vertex-only pipelines.
+        if (descriptor->fragmentStage == nullptr) {
+            return DAWN_VALIDATION_ERROR("Null fragment stage is not supported (yet)");
+        }
+
         std::bitset<kMaxVertexAttributes> attributesSetMask;
         DAWN_TRY(ValidateVertexInputDescriptor(descriptor->vertexInput, &attributesSetMask));
         DAWN_TRY(ValidatePrimitiveTopology(descriptor->primitiveTopology));