diff --git a/cloud/services/agentpools/agentpools.go b/cloud/services/agentpools/agentpools.go
index c3dd6c85d4a..736b314fb90 100644
--- a/cloud/services/agentpools/agentpools.go
+++ b/cloud/services/agentpools/agentpools.go
@@ -53,6 +53,7 @@ func (s *Service) Reconcile(ctx context.Context, spec interface{}) error {
 	profile := containerservice.AgentPool{
 		ManagedClusterAgentPoolProfileProperties: &containerservice.ManagedClusterAgentPoolProfileProperties{
 			VMSize:              containerservice.VMSizeTypes(agentPoolSpec.SKU),
+			OsType:              containerservice.Linux,
 			OsDiskSizeGB:        &agentPoolSpec.OSDiskSizeGB,
 			Count:               &agentPoolSpec.Replicas,
 			Type:                containerservice.VirtualMachineScaleSets,
@@ -87,6 +88,7 @@ func (s *Service) Reconcile(ctx context.Context, spec interface{}) error {
 		existingProfile := containerservice.AgentPool{
 			ManagedClusterAgentPoolProfileProperties: &containerservice.ManagedClusterAgentPoolProfileProperties{
 				VMSize:              existingPool.ManagedClusterAgentPoolProfileProperties.VMSize,
+				OsType:              containerservice.Linux,
 				OsDiskSizeGB:        existingPool.ManagedClusterAgentPoolProfileProperties.OsDiskSizeGB,
 				Count:               existingPool.ManagedClusterAgentPoolProfileProperties.Count,
 				Type:                containerservice.VirtualMachineScaleSets,
diff --git a/cloud/services/agentpools/agentpools_test.go b/cloud/services/agentpools/agentpools_test.go
index cb99f6ce71f..14ab066de89 100644
--- a/cloud/services/agentpools/agentpools_test.go
+++ b/cloud/services/agentpools/agentpools_test.go
@@ -243,6 +243,7 @@ func TestReconcile(t *testing.T) {
 						Count:               to.Int32Ptr(2),
 						OsDiskSizeGB:        to.Int32Ptr(100),
 						VMSize:              containerservice.VMSizeTypesStandardD2sV3,
+						OsType:              containerservice.Linux,
 						OrchestratorVersion: to.StringPtr("9.99.9999"),
 						ProvisioningState:   to.StringPtr("Succeeded"),
 						VnetSubnetID:        to.StringPtr(""),