diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc b/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
index c7fe9fa9a..60ed69cb2 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module.cc
@@ -19,6 +19,9 @@
 
 namespace webrtc {
 
+const char kLegacyAcmVersion[] = "acm1";
+const char kExperimentalAcmVersion[] = "acm2";
+
 // Create module
 AudioCodingModule* AudioCodingModule::Create(int id) {
   return new acm1::AudioCodingModuleImpl(id, Clock::GetRealTimeClock());
diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
index 59d5727a3..ce0521818 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
@@ -1975,6 +1975,10 @@ int AudioCodingModuleImpl::LeastRequiredDelayMs() const {
   return receiver_.LeastRequiredDelayMs();
 }
 
+const char* AudioCodingModuleImpl::Version() const {
+  return kExperimentalAcmVersion;
+}
+
 }  // namespace acm2
 
 }  // namespace webrtc
diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.h b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.h
index 6bf90cf26..17fab396c 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.h
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.h
@@ -32,12 +32,11 @@ class ACMGenericCodec;
 
 class AudioCodingModuleImpl : public AudioCodingModule {
  public:
-  // Constructor
   explicit AudioCodingModuleImpl(int id);
-
-  // Destructor
   ~AudioCodingModuleImpl();
 
+  virtual const char* Version() const;
+
   // Change the unique identifier of this object.
   virtual int32_t ChangeUniqueId(const int32_t id);
 
diff --git a/webrtc/modules/audio_coding/main/interface/audio_coding_module.h b/webrtc/modules/audio_coding/main/interface/audio_coding_module.h
index 2f4776d75..f8b9690f8 100644
--- a/webrtc/modules/audio_coding/main/interface/audio_coding_module.h
+++ b/webrtc/modules/audio_coding/main/interface/audio_coding_module.h
@@ -73,6 +73,10 @@ class ACMVQMonCallback {
       const uint16_t delayMS) = 0;  // average delay in ms
 };
 
+// Version string for testing, to distinguish instances of ACM1 from ACM2.
+extern const char kLegacyAcmVersion[];
+extern const char kExperimentalAcmVersion[];
+
 class AudioCodingModule: public Module {
  protected:
   AudioCodingModule() {}
@@ -174,6 +178,11 @@ class AudioCodingModule: public Module {
   //
   static bool IsCodecValid(const CodecInst& codec);
 
+  // Returns the version of ACM. This facilitates distinguishing instances of
+  // ACM1 from ACM2 while testing. This API will be removed when ACM1 is
+  // completely removed.
+  virtual const char* Version() const = 0;
+
   ///////////////////////////////////////////////////////////////////////////
   //   Sender
   //
diff --git a/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.cc b/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.cc
index 38027338a..1e71a0442 100644
--- a/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.cc
+++ b/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.cc
@@ -3026,6 +3026,10 @@ void AudioCodingModuleImpl::DisableNack() {
   nack_enabled_ = false;
 }
 
+const char* AudioCodingModuleImpl::Version() const {
+  return kLegacyAcmVersion;
+}
+
 }  // namespace acm1
 
 }  // namespace webrtc
diff --git a/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.h b/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.h
index 7d58f375a..7acde177d 100644
--- a/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.h
+++ b/webrtc/modules/audio_coding/main/source/audio_coding_module_impl.h
@@ -40,12 +40,11 @@ class ACMGenericCodec;
 
 class AudioCodingModuleImpl : public AudioCodingModule {
  public:
-  // Constructor
   AudioCodingModuleImpl(const int32_t id, Clock* clock);
-
-  // Destructor
   ~AudioCodingModuleImpl();
 
+  virtual const char* Version() const;
+
   // Change the unique identifier of this object.
   virtual int32_t ChangeUniqueId(const int32_t id);