diff --git a/tests/vsock_test.cc b/tests/vsock_test.cc
index 233c6dd..931e79d 100644
--- a/tests/vsock_test.cc
+++ b/tests/vsock_test.cc
@@ -86,7 +86,7 @@
     VirtualMachineConfig config;
     config.kernel = ParcelFileDescriptor(unique_fd(open(kVmKernelPath, O_RDONLY | O_CLOEXEC)));
     config.initrd = ParcelFileDescriptor(unique_fd(open(kVmInitrdPath, O_RDONLY | O_CLOEXEC)));
-    config.params = String16(kVmParams);
+    config.params = kVmParams;
     config.protected_vm = protected_vm;
 
     sp<IVirtualMachine> vm;
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/Partition.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/Partition.aidl
index 782c239..825c3da 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/Partition.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/Partition.aidl
@@ -18,7 +18,7 @@
 /** A partition to be assembled into a composite image. */
 parcelable Partition {
     /** A label for the partition. */
-    String label;
+    @utf8InCpp String label;
 
     /** The backing file descriptor of the partition image. */
     ParcelFileDescriptor image;
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineConfig.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineConfig.aidl
index cb28856..5d59f9d 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineConfig.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineConfig.aidl
@@ -29,7 +29,7 @@
      * Parameters to pass to the kernel. As far as the VMM and boot protocol are concerned this is
      * just a string, but typically it will contain multiple parameters separated by spaces.
      */
-    @nullable String params;
+    @nullable @utf8InCpp String params;
 
     /**
      * The bootloader to use. If this is supplied then the kernel and initrd must not be supplied;
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineDebugInfo.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineDebugInfo.aidl
index 18b01ce..d081b8d 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineDebugInfo.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/VirtualMachineDebugInfo.aidl
@@ -21,13 +21,13 @@
     int cid;
 
     /** Directory of temporary files used by the VM while it is running. */
-    String temporaryDirectory;
+    @utf8InCpp String temporaryDirectory;
 
     /** The UID of the process which requested the VM. */
     int requesterUid;
 
     /** The SID of the process which requested the VM. */
-    String requesterSid;
+    @utf8InCpp String requesterSid;
 
     /**
      * The PID of the process which requested the VM. Note that this process may no longer exist and