diff --git a/src/client.cpp b/src/client.cpp
index 01239a46..54bfc0bd 100755
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -92,8 +92,8 @@ CClient::CClient ( const quint16  iPortNumber,
     opus_custom_encoder_ctl ( OpusEncoderMono,
                               OPUS_SET_APPLICATION ( OPUS_APPLICATION_RESTRICTED_LOWDELAY ) );
 
-#ifdef USE_LOW_COMPLEXITY_CELT_ENC
-    // set encoder low complexity
+#if ( SYSTEM_FRAME_SIZE_SAMPLES == 128 )
+    // set encoder low complexity for legacy 128 samples frame size
     opus_custom_encoder_ctl ( OpusEncoderMono,
                               OPUS_SET_COMPLEXITY ( 1 ) );
 #endif
@@ -115,8 +115,8 @@ CClient::CClient ( const quint16  iPortNumber,
     opus_custom_encoder_ctl ( OpusEncoderStereo,
                               OPUS_SET_APPLICATION ( OPUS_APPLICATION_RESTRICTED_LOWDELAY ) );
 
-#ifdef USE_LOW_COMPLEXITY_CELT_ENC
-    // set encoder low complexity
+#if ( SYSTEM_FRAME_SIZE_SAMPLES == 128 )
+    // set encoder low complexity for legacy 128 samples frame size
     opus_custom_encoder_ctl ( OpusEncoderStereo,
                               OPUS_SET_COMPLEXITY ( 1 ) );
 #endif
diff --git a/src/global.h b/src/global.h
index a6fa0b90..6e2040ab 100755
--- a/src/global.h
+++ b/src/global.h
@@ -129,9 +129,6 @@ LED bar:      lbr
 #define FRAME_SIZE_FACTOR_DEFAULT       2 // 256 (for frame size 128), 128 (for frame size 64)
 #define FRAME_SIZE_FACTOR_SAFE          4 // 512 (for frame size 128), 256 (for frame size 64)
 
-// low complexity CELT encoder (if defined)
-#define USE_LOW_COMPLEXITY_CELT_ENC
-
 // define the minimum allowed number of coded bytes for CELT (the encoder
 // gets in trouble if the value is too low)
 #define CELT_MINIMUM_NUM_BYTES          10
diff --git a/src/server.cpp b/src/server.cpp
index 5bc68531..3cdcb096 100755
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -266,8 +266,8 @@ CServer::CServer ( const int          iNewMaxNumChan,
         opus_custom_encoder_ctl ( OpusEncoderMono[i],
                                   OPUS_SET_APPLICATION ( OPUS_APPLICATION_RESTRICTED_LOWDELAY ) );
 
-#ifdef USE_LOW_COMPLEXITY_CELT_ENC
-        // set encoder low complexity
+#if ( SYSTEM_FRAME_SIZE_SAMPLES == 128 )
+        // set encoder low complexity for legacy 128 samples frame size
         opus_custom_encoder_ctl ( OpusEncoderMono[i],
                                   OPUS_SET_COMPLEXITY ( 1 ) );
 #endif
@@ -289,8 +289,8 @@ CServer::CServer ( const int          iNewMaxNumChan,
         opus_custom_encoder_ctl ( OpusEncoderStereo[i],
                                   OPUS_SET_APPLICATION ( OPUS_APPLICATION_RESTRICTED_LOWDELAY ) );
 
-#ifdef USE_LOW_COMPLEXITY_CELT_ENC
-        // set encoder low complexity
+#if ( SYSTEM_FRAME_SIZE_SAMPLES == 128 )
+        // set encoder low complexity for legacy 128 samples frame size
         opus_custom_encoder_ctl ( OpusEncoderStereo[i],
                                   OPUS_SET_COMPLEXITY ( 1 ) );
 #endif