diff --git a/source/plugin/carla-vst.cpp b/source/plugin/carla-vst.cpp
index 34ddb8331..4dcf974e5 100644
--- a/source/plugin/carla-vst.cpp
+++ b/source/plugin/carla-vst.cpp
@@ -211,17 +211,17 @@ public:
                 carla_zeroStruct<NativeTimeInfo>(fTimeInfo);
 
                 // tell host we want MIDI events
-                masterCallback(audioMasterWantMidi);
+                hostCallback(audioMasterWantMidi);
 
                 // deactivate for possible changes
                 if (fDescriptor->deactivate != nullptr && fIsActive)
                     fDescriptor->deactivate(fHandle);
 
                 // check if something changed
-                const uint32_t bufferSize = static_cast<uint32_t>(masterCallback(audioMasterGetBlockSize));
-                const double   sampleRate = static_cast<double>(masterCallback(audioMasterGetSampleRate));
+                const uint32_t bufferSize = static_cast<uint32_t>(hostCallback(audioMasterGetBlockSize));
+                const double   sampleRate = static_cast<double>(hostCallback(audioMasterGetSampleRate));
 
-                if (fBufferSize != bufferSize)
+                if (bufferSize != 0 && fBufferSize != bufferSize)
                 {
                     fBufferSize = bufferSize;
 
@@ -229,7 +229,7 @@ public:
                         fDescriptor->dispatcher(fHandle, NATIVE_PLUGIN_OPCODE_BUFFER_SIZE_CHANGED, 0, (int32_t)value, nullptr, 0.0f);
                 }
 
-                if (! carla_compareFloats(fSampleRate, sampleRate))
+                if (sampleRate != 0.0 && ! carla_compareFloats(fSampleRate, sampleRate))
                 {
                     fSampleRate = sampleRate;
 
@@ -270,7 +270,7 @@ public:
 
                 // check if vst host is tracktion
                 carla_zeroChar(strBuf, 0xff+1);
-                masterCallback(audioMasterGetProductString, 0, 0, strBuf, 0.0f);
+                hostCallback(audioMasterGetProductString, 0, 0, strBuf, 0.0f);
 
                 const bool isTracktion(std::strcmp(strBuf, "Tracktion") == 0);
 
@@ -293,7 +293,7 @@ public:
 
                     for (int x=10; --x>=0;)
                     {
-                        masterCallback(audioMasterIdle);
+                        hostCallback(audioMasterIdle);
                         carla_msleep(25);
                     }
                 }
@@ -349,7 +349,6 @@ public:
             {
                 // host has not activated the plugin yet, nasty!
                 vst_dispatcher(effMainsChanged, 0, 1, nullptr, 0.0f);
-                fIsActive = true;
             }
 
             if (const VstEvents* const events = (const VstEvents*)ptr)
@@ -418,12 +417,11 @@ public:
         {
             // host has not activated the plugin yet, nasty!
             vst_dispatcher(effMainsChanged, 0, 1, nullptr, 0.0f);
-            fIsActive = true;
         }
 
         static const int kWantVstTimeFlags(kVstTransportPlaying|kVstPpqPosValid|kVstTempoValid|kVstTimeSigValid);
 
-        if (const VstTimeInfo* const vstTimeInfo = (const VstTimeInfo*)masterCallback(audioMasterGetTime, 0, kWantVstTimeFlags))
+        if (const VstTimeInfo* const vstTimeInfo = (const VstTimeInfo*)hostCallback(audioMasterGetTime, 0, kWantVstTimeFlags))
         {
             fTimeInfo.frame     = static_cast<uint64_t>(vstTimeInfo->samplePos);
             fTimeInfo.playing   =  (vstTimeInfo->flags & kVstTransportPlaying);
@@ -469,7 +467,7 @@ public:
         fMidiEventCount = 0;
 
         if (fMidiOutEvents.numEvents > 0)
-            masterCallback(audioMasterProcessEvents, 0, 0, &fMidiOutEvents, 0.0f);
+            hostCallback(audioMasterProcessEvents, 0, 0, &fMidiOutEvents, 0.0f);
     }
 
 protected:
@@ -558,7 +556,7 @@ protected:
             break;
 
         case NATIVE_HOST_OPCODE_HOST_IDLE:
-            masterCallback(audioMasterIdle);
+            hostCallback(audioMasterIdle);
             break;
         }
 
@@ -590,11 +588,11 @@ private:
     ERect           fVstRect;
 
     // host callback
-    intptr_t masterCallback(const int32_t opcode,
-                            const int32_t index = 0,
-                            const intptr_t value = 0,
-                            void* const ptr = nullptr,
-                            const float opt = 0.0f)
+    intptr_t hostCallback(const int32_t opcode,
+                          const int32_t index = 0,
+                          const intptr_t value = 0,
+                          void* const ptr = nullptr,
+                          const float opt = 0.0f)
     {
         return fAudioMaster(fEffect, opcode, index, value, ptr, opt);
     }