diff --git a/lib/constellation.cc b/lib/constellation.cc
index 5e10a25..62e4a34 100644
--- a/lib/constellation.cc
+++ b/lib/constellation.cc
@@ -135,9 +135,11 @@ namespace gr {
             uint16_t idx(0);
             for(int j=0; j<d_bps; j++){
                 // sanity check - hopefully this does not slow things down too much
+#ifndef _MSC_VER
                 if(__builtin_expect( in[i*d_bps + j] > 0x01, false)){
                     throw std::runtime_error((boost::format("ERROR: constellation mapper expects values of 0x00 and 0x01 in *ONLY* - received 0x%02x at bit offset %d!")% ((int)(in[i*d_bps+j]))%(d_bps*i)).str());
                 }
+#endif // !_MSC_VER
                 idx |= (in[i*d_bps + j] << (d_bps - j-1));
             }
             out[i] = d_mappings[mapidx][idx];
diff --git a/lib/pream_sync_correlator.cc b/lib/pream_sync_correlator.cc
index c5da0f3..bdf7435 100644
--- a/lib/pream_sync_correlator.cc
+++ b/lib/pream_sync_correlator.cc
@@ -46,7 +46,7 @@ namespace gr {
         d_in_stream.push_back(gr_complex(0,0));
       }
       d_in_stream.push_back(gr_complex(0,0));
-      float phase[N];
+      __GR_VLA(float, phase, N);
       for(int idx = 1; idx < N; idx++){
         phase[idx] = arg(d_preamble_symbols[idx]);
       }
@@ -99,13 +99,13 @@ namespace gr {
     }
 
     float pream_sync_correlator::acquire_value(void){
-      float phase[d_preamble_symbol_count];
+      __GR_VLA(float, phase, d_preamble_symbol_count);
       for(int idx=0; idx < d_preamble_symbol_count; idx++){
         phase[idx] = arg(d_in_stream[d_preamble_symbol_count - 1 - idx]);
 //          printf("\t1: sa[%02d] = (%02.4f,%02.4f), phase[%02d] = %02.4f\n",idx,small_array[idx].real(),small_array[idx].imag(),idx,phase[idx]);
       }
       unwrap(phase, d_preamble_symbol_count);
-      float phase_change[d_preamble_symbol_count];
+      __GR_VLA(float, phase_change, d_preamble_symbol_count);
       float phase_diff = 0.0;//[d_preamble_symbol_count-1];
       phase_change[0] = 0.0;
 //      phase_diff[idx] = 0.0;
@@ -132,10 +132,10 @@ namespace gr {
     }
     
     void pream_sync_correlator::unwrap(float *phase_array, int N) {
-      float dp[N];
-      float dps[N];
-      float dp_corr[N];
-      float cumsum[N];
+      __GR_VLA(float, dp, N);
+      __GR_VLA(float, dps, N);
+      __GR_VLA(float, dp_corr, N);
+      __GR_VLA(float, cumsum, N);
       float cutoff = M_PI;
       int j;
 
diff --git a/lib/preamble_sync_cc_impl.cc b/lib/preamble_sync_cc_impl.cc
index c50b410..e5fa1e4 100644
--- a/lib/preamble_sync_cc_impl.cc
+++ b/lib/preamble_sync_cc_impl.cc
@@ -99,7 +99,7 @@ namespace gr {
         int search_space = (int) d_preamble.size()/d_interp;
         int data_space = d_width/d_interp - search_space;
         int payload_space = d_width/d_interp;
-        float phase[search_space];
+        __GR_VLA(float, phase, search_space);
         if(d_early_term) {
           d_corr.reset();
           d_state = 0;
@@ -307,12 +307,12 @@ namespace gr {
       }
       //for(int ind = 0; ind<d_preamble.size()/d_interp; ind++){ printf("d_preamble_map[%d] = (%f, %f)\n",ind,d_preamble_map[ind].real(),d_preamble_map[ind].imag()); }
       d_mapidx = (d_mapidx + d_preamble.size()/d_interp)%d_const.nmaps();
-      float phase[int(d_preamble.size()/d_interp)];
+      __GR_VLA(float, phase, int(d_preamble.size() / d_interp));
       for(int idx = 0; idx < d_preamble.size()/d_interp; idx++){
         phase[idx] = arg(d_preamble_map[idx]);
       }
       unwrap(phase,(int)d_preamble.size()/d_interp);
-      float phase_change[d_preamble.size()/d_interp];
+      __GR_VLA(float, phase_change, d_preamble.size() / d_interp);
       phase_change[0] = 0.0;
       for(int ind = 1; ind < d_preamble.size()/d_interp; ind++) {
         phase_change[ind] = phase[ind] - phase[ind-1];
@@ -323,10 +323,10 @@ namespace gr {
     }
     
     void preamble_sync_cc_impl::unwrap(float *phase_array, int N) {
-      float dp[N];
-      float dps[N];
-      float dp_corr[N];
-      float cumsum[N];
+      __GR_VLA(float, dp, N);
+      __GR_VLA(float, dps, N);
+      __GR_VLA(float, dp_corr, N);
+      __GR_VLA(float, cumsum, N);
       float cutoff = M_PI;
       int j;
 
diff --git a/lib/preamble_sync_demapper_hard_impl.cc b/lib/preamble_sync_demapper_hard_impl.cc
index 648176e..003c74e 100644
--- a/lib/preamble_sync_demapper_hard_impl.cc
+++ b/lib/preamble_sync_demapper_hard_impl.cc
@@ -149,7 +149,7 @@ namespace gr {
               }
               //printf("Compare has shifted.\t Pream_len = %d\n",pream_len);
               for(int idx=0; idx < MN; idx++){
-                uint8_t symbol_bits[d_bps];
+                __GR_VLA(uint8_t, symbol_bits, d_bps);
                 gr_complex symbol = in[ii] * exp(gr_complex(0,2*M_PI*idx/MN));
                 d_const.demap_hard(&symbol, &symbol_bits[0], 1);
                 for(int ind = d_bps; ind > 0; ind--){
@@ -158,7 +158,7 @@ namespace gr {
                 }
               }
               //printf("Compare has updated.\n");
-              int ham_dist[MN];
+              __GR_VLA(int, ham_dist, MN);
               for(int idx=0; idx < MN; idx++){ ham_dist[idx] = 0; }
               for(int idx=0; idx < MN; idx++){
                 //printf("idx = %d of MN = %d\t",idx,MN);
@@ -225,7 +225,7 @@ namespace gr {
               }
               //float soft_out[n_symbols*d_bps];
               //d_const.demap_soft(&in_rotated[0], &soft_out[0], n_symbols);
-              uint8_t hard_out[n_symbols*d_bps];
+              __GR_VLA(uint8_t, hard_out, n_symbols * d_bps);
               d_const.demap_hard(&in_rotated[0], &hard_out[0], n_symbols);
               //memcpy(&out[oo], &soft_out[0], sizeof(float)*n_symbols*d_bps);
               memcpy(&out[oo], &hard_out[0], sizeof(uint8_t)*n_symbols*d_bps);
diff --git a/lib/preamble_sync_demapper_impl.cc b/lib/preamble_sync_demapper_impl.cc
index 5298809..0dbbe69 100644
--- a/lib/preamble_sync_demapper_impl.cc
+++ b/lib/preamble_sync_demapper_impl.cc
@@ -149,7 +149,7 @@ namespace gr {
               }
               //printf("Compare has shifted.\t Pream_len = %d\n",pream_len);
               for(int idx=0; idx < MN; idx++){
-                uint8_t symbol_bits[d_bps];
+                __GR_VLA(uint8_t, symbol_bits, d_bps);
                 gr_complex symbol = in[ii] * exp(gr_complex(0,2*M_PI*idx/MN));
                 d_const.demap_hard(&symbol, &symbol_bits[0], 1);
                 for(int ind = d_bps; ind > 0; ind--){
@@ -158,7 +158,7 @@ namespace gr {
                 }
               }
               //printf("Compare has updated.\n");
-              int ham_dist[MN];
+              __GR_VLA(int, ham_dist, MN);
               for(int idx=0; idx < MN; idx++){ ham_dist[idx] = 0; }
               for(int idx=0; idx < MN; idx++){
                 //printf("idx = %d of MN = %d\t",idx,MN);
@@ -223,7 +223,7 @@ namespace gr {
               for(int idx = 0; idx < n_symbols; idx++){
                 in_rotated[idx] = in[start_pointer+idx] * exp(gr_complex(0,2*M_PI*d_offset/MN));
               }
-              float soft_out[n_symbols*d_bps];
+              __GR_VLA(float, soft_out, n_symbols * d_bps);
               d_const.demap_soft(&in_rotated[0], &soft_out[0], n_symbols);
               //uint8_t hard_out[n_symbols*d_bps];
               //d_const.demap_hard(&in_rotated[0], &hard_out[0], n_symbols);