diff --git a/rogueviz/sag/annealing.cpp b/rogueviz/sag/annealing.cpp
index e96595de..d5550cff 100644
--- a/rogueviz/sag/annealing.cpp
+++ b/rogueviz/sag/annealing.cpp
@@ -144,7 +144,7 @@ void dofullsa(ld satime) {
     
     if(t2 - tl > view_each * .98) {
       tl = t2;
-      println(hlog, format("it %12Ld temp %6.4f [1/e at %13.6f] cost = %f ",
+      println(hlog, format("it %12lld temp %6.4f [1/e at %13.6f] cost = %f ",
         numiter, double(sag::temperature), (double) exp(sag::temperature),
         double(sag::cost)));
       }
@@ -205,7 +205,7 @@ void dofullsa_iterations(long long saiter) {
 
     if(cpct > lpct && output_fullsa) {
       lpct = cpct;
-      println(hlog, format("it %12Ld ratio %6.3f temp %8.4f step %9.3g cost %9.2f R=%8.4f T=%8.4f",
+      println(hlog, format("it %12lld ratio %6.3f temp %8.4f step %9.3g cost %9.2f R=%8.4f T=%8.4f",
         numiter, last_ratio, double(sag::temperature), (double) exp(sag::temperature), cost, lgsag.R, lgsag.T));
       }
 
diff --git a/rogueviz/sag/cells.cpp b/rogueviz/sag/cells.cpp
index cdc03c3b..af7f2e6d 100644
--- a/rogueviz/sag/cells.cpp
+++ b/rogueviz/sag/cells.cpp
@@ -79,7 +79,7 @@ struct sagdist_t {
     clear();
     fd = open(fname.c_str(), O_RDONLY | O_LARGEFILE);
     if(fd == -1) throw hr_exception("open failed in map");
-    read(fd, &N, 8);
+    if(read(fd, &N, 8) < 8) throw hr_exception("file error");
     tabmap = (distance*) mmap(nullptr, N*N*sizeof(distance)+8, PROT_READ, MAP_SHARED, fd, 0);
 
 
@@ -117,7 +117,7 @@ struct sagdist_t {
 
   void save(string fname) {
     fd = open(fname.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0666);
-    write(fd, &N, 8);
+    if(write(fd, &N, 8) < 8) throw hr_exception("write error");
     size_t size =  N*N*sizeof(distance);
     println(hlog, "size is ", hr::format("%zd", size));
     char *p = (char*) tab;
diff --git a/rogueviz/sag/data.cpp b/rogueviz/sag/data.cpp
index 8e4435c0..2d5b0631 100644
--- a/rogueviz/sag/data.cpp
+++ b/rogueviz/sag/data.cpp
@@ -173,7 +173,7 @@ void load_sag_solution(const string& fname) {
 void load_sag_solution_basic(const string& fname) {
   if(!(state & SS_DATA)) throw hr_exception("load_sag_solution_basic with no data");
   FILE *f = fopen(fname.c_str(), "rt");
-  for(auto& i: sagid) fscanf(f, "%d", &i);
+  for(auto& i: sagid) if(fscanf(f, "%d", &i) < 1) throw hr_exception("read error in load_sag_solution_basic");
   fclose(f);
   println(hlog, "loaded sagid = ", sagid);
 
diff --git a/rogueviz/sag/sag.cpp b/rogueviz/sag/sag.cpp
index 0f0c02e7..c04f7a06 100644
--- a/rogueviz/sag/sag.cpp
+++ b/rogueviz/sag/sag.cpp
@@ -41,7 +41,7 @@ void iterate() {
   if(t < (sag_ittime+1) / 2) ipturn *= 2;
   else if(t > sag_ittime * 2) ipturn /= 2;
   else ipturn = ipturn * sag_ittime / t;
-  print(hlog, format("it %12Ld temp %6.4f [2:%8.6f,10:%8.6f,50:%8.6f] cost = %f\n",
+  print(hlog, format("it %12lld temp %6.4f [2:%8.6f,10:%8.6f,50:%8.6f] cost = %f\n",
     numiter, double(sag::temperature), 
     (double) exp(-2 * exp(-sag::temperature)),
     (double) exp(-10 * exp(-sag::temperature)),