diff --git a/core/src/dsp/demodulator.h b/core/src/dsp/demodulator.h
index 67126c5e..26dd0404 100644
--- a/core/src/dsp/demodulator.h
+++ b/core/src/dsp/demodulator.h
@@ -145,11 +145,8 @@ namespace dsp {
         }
 
         void setDeviation(float deviation) {
-            std::lock_guard<std::mutex> lck(generic_block<FMDemod>::ctrlMtx);
-            generic_block<FMDemod>::tempStop();
             _deviation = deviation;
             phasorSpeed = (2 * FL_M_PI) / (_sampleRate / _deviation);
-            generic_block<FMDemod>::tempStart();
         }
 
         float getDeviation() {
diff --git a/core/src/dsp/filter.h b/core/src/dsp/filter.h
index b77ac1ff..e02bd71e 100644
--- a/core/src/dsp/filter.h
+++ b/core/src/dsp/filter.h
@@ -41,10 +41,12 @@ namespace dsp {
         }
 
         void updateWindow(dsp::filter_window::generic_window* window) {
+            std::lock_guard<std::mutex> lck(generic_block<FIR<T>>::ctrlMtx);
             _window = window;
             volk_free(taps);
             tapCount = window->getTapCount();
             taps = (float*)volk_malloc(tapCount * sizeof(float), volk_get_alignment());
+            bufStart = &buffer[tapCount];
             window->createTaps(taps, tapCount);
         }
 
@@ -52,6 +54,8 @@ namespace dsp {
             int count = _in->read();
             if (count < 0) { return -1; }
 
+            generic_block<FIR<T>>::ctrlMtx.lock();
+
             memcpy(bufStart, _in->readBuf, count * sizeof(T));
             _in->flush();
 
@@ -70,6 +74,8 @@ namespace dsp {
 
             memmove(buffer, &buffer[count], tapCount * sizeof(T));
 
+            generic_block<FIR<T>>::ctrlMtx.unlock();
+
             return count;
         }