diff --git a/lxd/api_project.go b/lxd/api_project.go
index 5e75f1ca5d41..693ec8954844 100644
--- a/lxd/api_project.go
+++ b/lxd/api_project.go
@@ -599,14 +599,14 @@ func projectPatch(d *Daemon, r *http.Request) response.Response {
 		req.Description = project.Description
 	}
 
-	config, err := reqRaw.GetMap("config")
-	if err != nil {
-		req.Config = project.Config
-	} else {
-		for k, v := range project.Config {
-			_, ok := config[k]
-			if !ok {
-				config[k] = v
+	// Perform config patch
+	req.Config = util.CopyConfig(project.Config)
+	patches, err := reqRaw.GetMap("config")
+	if err == nil {
+		for k, v := range patches {
+			strVal, ok := v.(string)
+			if ok {
+				req.Config[k] = strVal
 			}
 		}
 	}
diff --git a/test/suites/projects.sh b/test/suites/projects.sh
index a1269b97c2ba..5af0bc750ac7 100644
--- a/test/suites/projects.sh
+++ b/test/suites/projects.sh
@@ -20,6 +20,10 @@ test_projects_crud() {
   lxc project show foo | grep -q 'features.images: "true"'
   lxc project get foo "features.profiles" | grep -q 'true'
 
+  # Set a limit
+  lxc project set foo limits.containers 10
+  lxc project show foo | grep -q 'limits.containers: "10"'
+
   # Trying to create a project with the same name fails
   ! lxc project create foo || false
 
@@ -37,6 +41,13 @@ test_projects_crud() {
   lxc project show bar| sed 's/^description:.*/description: "Bar project"/' | lxc project edit bar
   lxc project show bar | grep -q "description: Bar project"
 
+  # Edit the project config via PATCH. Existing key/value pairs should remain or be updated.
+  lxc query -X PATCH -d '{\"config\" : {\"limits.memory\":\"5GiB\",\"features.images\":\"false\"}}' /1.0/projects/bar
+  lxc project show bar | grep -q 'limits.memory: 5GiB'
+  lxc project show bar | grep -q 'features.images: "false"'
+  lxc project show bar | grep -q 'features.profiles: "true"'
+  lxc project show bar | grep -q 'limits.containers: "10"'
+
   # Create a second project
   lxc project create foo