diff --git a/csdr.c b/csdr.c
index 2951d8f..3a78c2b 100755
--- a/csdr.c
+++ b/csdr.c
@@ -2778,6 +2778,7 @@ int main(int argc, char *argv[])
         sscanf(argv[4],"%f",&gain);
 
         int decision_directed = !!(argc>5 && (!strcmp(argv[5], "--dd") || !strcmp(argv[5], "--decision_directed")));
+        if(decision_directed) fprintf(stderr, "csdr bpsk_costas_loop_cc: decision directed mode\n");
 
         bpsk_costas_loop_state_t state;
         init_bpsk_costas_loop_cc(&state, decision_directed, damping_factor, loop_bandwidth, gain);
diff --git a/grc_tests/test_bpsk_costas_loop.grc b/grc_tests/test_bpsk_costas_loop.grc
index 0abca69..b8d1183 100644
--- a/grc_tests/test_bpsk_costas_loop.grc
+++ b/grc_tests/test_bpsk_costas_loop.grc
@@ -140,7 +140,7 @@
     </param>
     <param>
       <key>value</key>
-      <value>0</value>
+      <value>10</value>
     </param>
     <param>
       <key>_enabled</key>
@@ -180,7 +180,7 @@
     </param>
     <param>
       <key>num_steps</key>
-      <value>100</value>
+      <value>1000</value>
     </param>
     <param>
       <key>style</key>
@@ -693,7 +693,7 @@
     </param>
     <param>
       <key>commandline</key>
-      <value>csdr bpsk_costas_loop_cc $(csdr =2*pi/100) 0.707 1  </value>
+      <value>csdr bpsk_costas_loop_cc $(csdr =2*pi/100) 0.707 300 --dd 2&gt;/tmp/cout</value>
     </param>
     <param>
       <key>comment</key>
diff --git a/libcsdr.c b/libcsdr.c
index d06bb5d..436c589 100755
--- a/libcsdr.c
+++ b/libcsdr.c
@@ -2100,10 +2100,12 @@ void bpsk_costas_loop_cc(complexf* input, complexf* output, int input_size, bpsk
         else error = iof(output,i)*qof(output,i);
         s->dphase = error * s->alpha + s->iir_temp;
         s->iir_temp += error * s->beta;
+        fprintf(stderr, "  error = %f, dphase = %f, nco_phase = %f\n", error, s->dphase, s->nco_phase);
 
         //step NCO
         s->nco_phase += s->dphase;
         while(s->nco_phase>2*PI) s->nco_phase-=2*PI;
+        while(s->nco_phase<=0) s->nco_phase+=2*PI;
     }
 }