diff --git a/source/backend/engine/CarlaEngineRtAudio.cpp b/source/backend/engine/CarlaEngineRtAudio.cpp
index a78e0f701..d99d642a4 100644
--- a/source/backend/engine/CarlaEngineRtAudio.cpp
+++ b/source/backend/engine/CarlaEngineRtAudio.cpp
@@ -23,7 +23,7 @@
 #include "rtaudio/RtAudio.h"
 #include "rtmidi/RtMidi.h"
 
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
 # include "juce_audio_basics.h"
 using juce::FloatVectorOperations;
 #endif
@@ -839,8 +839,10 @@ protected:
         {
             if (fAudioCountOut > 0 && fAudioIsReady)
             {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::clear(outsPtr, nframes*fAudioCountOut);
+#else
+                carla_zeroFloat(outsPtr, nframes*fAudioCountOut);
 #endif
             }
 
@@ -862,19 +864,28 @@ protected:
         {
             for (unsigned int i=0; i < fAudioCountIn; ++i)
             {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::copy(fAudioBufIn[i], insPtr+(nframes*i), nframes);
+#else
+                carla_copyFloat(fAudioBufIn[i], insPtr+(nframes*i), nframes);
 #endif
             }
         }
 
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
         // initialize audio output
         for (unsigned int i=0; i < fAudioCountOut; ++i)
             FloatVectorOperations::clear(fAudioBufOut[i], nframes);
 
         FloatVectorOperations::clear(fAudioBufRackOut[0], nframes);
         FloatVectorOperations::clear(fAudioBufRackOut[1], nframes);
+#else
+        // initialize audio output
+        for (unsigned int i=0; i < fAudioCountOut; ++i)
+            carla_zeroFloat(fAudioBufOut[i], nframes);
+
+        carla_zeroFloat(fAudioBufRackOut[0], nframes);
+        carla_zeroFloat(fAudioBufRackOut[1], nframes);
 #endif
 
         // initialize input events
@@ -916,8 +927,10 @@ protected:
         // connect input buffers
         if (fConnectedAudioIns[0].count() == 0)
         {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
             FloatVectorOperations::clear(fAudioBufRackIn[0], nframes);
+#else
+            carla_zeroFloat(fAudioBufRackIn[0], nframes);
 #endif
         }
         else
@@ -931,31 +944,39 @@ protected:
 
                 if (first)
                 {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                     FloatVectorOperations::copy(fAudioBufRackIn[0], fAudioBufIn[port], nframes);
+#else
+                    carla_copyFloat(fAudioBufRackIn[0], fAudioBufIn[port], nframes);
 #endif
                     first = false;
                 }
                 else
                 {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                     FloatVectorOperations::add(fAudioBufRackIn[0], fAudioBufIn[port], nframes);
+#else
+                    carla_addFloat(fAudioBufRackIn[0], fAudioBufIn[port], nframes);
 #endif
                 }
             }
 
             if (first)
             {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::clear(fAudioBufRackIn[0], nframes);
+#else
+                carla_zeroFloat(fAudioBufRackIn[0], nframes);
 #endif
             }
         }
 
         if (fConnectedAudioIns[1].count() == 0)
         {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
             FloatVectorOperations::clear(fAudioBufRackIn[1], nframes);
+#else
+            carla_zeroFloat(fAudioBufRackIn[1], nframes);
 #endif
         }
         else
@@ -969,23 +990,29 @@ protected:
 
                 if (first)
                 {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                     FloatVectorOperations::copy(fAudioBufRackIn[1], fAudioBufIn[port], nframes);
+#else
+                    carla_copyFloat(fAudioBufRackIn[1], fAudioBufIn[port], nframes);
 #endif
                     first = false;
                 }
                 else
                 {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                     FloatVectorOperations::add(fAudioBufRackIn[1], fAudioBufIn[port], nframes);
+#else
+                    carla_addFloat(fAudioBufRackIn[1], fAudioBufIn[port], nframes);
 #endif
                 }
             }
 
             if (first)
             {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::clear(fAudioBufRackIn[1], nframes);
+#else
+                carla_zeroFloat(fAudioBufRackIn[1], nframes);
 #endif
             }
         }
@@ -1001,8 +1028,10 @@ protected:
                 const uint& port(*it);
                 CARLA_ASSERT(port < fAudioCountOut);
 
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::add(fAudioBufOut[port], fAudioBufRackOut[0], nframes);
+#else
+                carla_addFloat(fAudioBufOut[port], fAudioBufRackOut[0], nframes);
 #endif
             }
         }
@@ -1014,8 +1043,10 @@ protected:
                 const uint& port(*it);
                 CARLA_ASSERT(port < fAudioCountOut);
 
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::add(fAudioBufOut[port], fAudioBufRackOut[1], nframes);
+#else
+                carla_addFloat(fAudioBufOut[port], fAudioBufRackOut[1], nframes);
 #endif
             }
         }
@@ -1037,8 +1068,10 @@ protected:
         {
             for (unsigned int i=0; i < fAudioCountOut; ++i)
             {
-#ifdef USE_JUCE
+#ifdef HAVE_JUCE
                 FloatVectorOperations::copy(outsPtr+(nframes*i), fAudioBufOut[i], nframes);
+#else
+                carla_copyFloat(outsPtr+(nframes*i), fAudioBufOut[i], nframes);
 #endif
             }
         }