diff --git a/src/Makefile b/src/Makefile
index e6ef0b7..4a143b2 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -25,10 +25,10 @@ CFLAGS = -g -O3 -march=corei7 -msse4.2 -pipe -D_GNU_SOURCE -Wall -std=c99 -Wstri
 
 export FLAGS CC CFLAGS
 
+all: rtbgen rtbgenp rtbver rtbverp tbcheck
+
 rtbgen rtbgenp rtbver rtbverp tbcheck clean:
 	@$(MAKE) -f Makefile.regular $@
 
-all: rtbgen rtbgenp rtbver rtbverp tbcheck
-
 .PHONY: rtbgen rtbgenp rtbver rtbverp tbcheck clean
 
diff --git a/src/checksum.c b/src/checksum.c
index 12c1aab..528739e 100644
--- a/src/checksum.c
+++ b/src/checksum.c
@@ -59,7 +59,7 @@ static void calc_checksum(char *name)
     checksum_found = 1;
   } else {
     if (size & 0x3f) {
-      printf("Size of %s is not a multiple of 64.\n", name);
+      fprintf(stderr, "Size of %s is not a multiple of 64.\n", name);
       exit(1);
     }
     checksum_found = 0;
@@ -84,7 +84,7 @@ void print_checksum(char *name, char *sum)
   if ((size & 0x3f) == 0x10) {
     memcpy(checksum1, data + (size & ~0x3fULL), 16);
   } else {
-    printf("No checksum found.\n");
+    fprintf(stderr, "No checksum found.\n");
     exit(1);
   }
   unmap_file(data, size);
@@ -105,12 +105,12 @@ void add_checksum(char *name)
 {
   calc_checksum(name);
   if (checksum_found) {
-    printf("%s checksum already present.\n", checksum_match ? "Matching" : "Non-matching");
+    fprintf(stderr, "%s checksum already present.\n", checksum_match ? "Matching" : "Non-matching");
     exit(1);
   }
   FILE *F = fopen(name, "ab");
   if (!F) {
-    printf("Could not open %s for appending.\n", name);
+    fprintf(stderr, "Could not open %s for appending.\n", name);
     exit(1);
   }
   fwrite(checksum2, 16, 1, F);
@@ -122,7 +122,7 @@ void verify_checksum(char *name)
   printf("%s: ", name);
   calc_checksum(name);
   if (!checksum_found) {
-    printf("No checksum present.\n");
+    fprintf(stderr, "No checksum present.\n");
     exit(1);
   }
   if (!checksum_match)
diff --git a/src/compress.c b/src/compress.c
index 7a108fb..303878c 100644
--- a/src/compress.c
+++ b/src/compress.c
@@ -993,7 +993,7 @@ struct HuffCode *construct_pairs_dtz(unsigned char *restrict data, long64 size,
       pairfreq[i][j] = 0;
 
   if (num_syms > 255) {
-    printf("error\n");
+    fprintf(stderr, "error\n");
     exit(1);
   }
   for (t = 0; t < numthreads; t++)
@@ -1107,7 +1107,7 @@ struct HuffCode *construct_pairs_dtz(unsigned char *restrict data, long64 size,
     }
 
     if (i != num) {
-      printf("Ran short of symbols.\n");
+      printf("Ran short of symbols.\n"); // not an error
       num = i;
       num_ctrl--;
     }
@@ -1738,7 +1738,7 @@ void compress_tb(struct tb_handle *F, ubyte *restrict data,
     strcat(name, F->wdl ? WDLSUFFIX : DTZSUFFIX);
     strcat(name, ext);
     if (!(G = fopen(name, "wb"))) {
-      printf("Could not open %s for writing.\n", name);
+      fprintf(stderr, "Could not open %s for writing.\n", name);
       exit(1);
     }
 
@@ -1760,7 +1760,7 @@ void merge_tb(struct tb_handle *F)
   strcpy(name, F->name);
   strcat(name, F->wdl ? WDLSUFFIX : DTZSUFFIX);
   if (!(G = fopen(name, "wb"))) {
-    printf("Could not open %s for writing.\n", name);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
     exit(1);
   }
 
@@ -1771,7 +1771,7 @@ void merge_tb(struct tb_handle *F)
     strcat(name, F->wdl ? WDLSUFFIX : DTZSUFFIX);
     strcat(name, ext);
     if (!(F->H[i] = fopen(name, "rb"))) {
-      printf("Could not open %s for reading.\n", name);
+      fprintf(stderr, "Could not open %s for reading.\n", name);
       exit(1);
     }
   }
diff --git a/src/decompress.c b/src/decompress.c
index 950f226..27a986f 100644
--- a/src/decompress.c
+++ b/src/decompress.c
@@ -273,7 +273,7 @@ void decomp_init_table(struct tb_handle *H)
   magic = 0;
   fread(&magic, 1, 4, F);
   if (magic != (H->wdl ? WDL_MAGIC : DTZ_MAGIC)) {
-    printf("Corrupted table.\n");
+    fprintf(stderr, "Corrupted table.\n");
     exit(1);
   }
 
@@ -468,7 +468,7 @@ static void decompress_worker(struct thread_data *thread)
     while (idx + size > idx2) {
       if (*((uint32 *)(d->indextable + 6 * mainidx)) != block
 	      || *((ushort *)(d->indextable + 6 * mainidx + 4)) != idx2 - idx) {
-	printf("ERROR in main index!!\n");
+	fprintf(stderr, "ERROR in main index!!\n");
 	exit(1);
       }
       idx2 += 1ULL << d->idxbits;
@@ -536,7 +536,7 @@ struct tb_handle *open_tb(char *tablename, int wdl)
   strcat(name, tablename);
   strcat(name, wdl ? WDLSUFFIX : DTZSUFFIX);
   if (!(H->F = fopen(name, "rb"))) {
-    printf("Could not open %s for reading.\n", name);
+    fprintf(stderr, "Could not open %s for reading.\n", name);
     exit(1);
   }
   H->data = (ubyte *)map_file(name, 1, &(H->data_size));
diff --git a/src/permute.c b/src/permute.c
index 1e94d8f..5e9ca36 100644
--- a/src/permute.c
+++ b/src/permute.c
@@ -1000,7 +1000,7 @@ ubyte *init_permute_piece(int *pcs, int *pt, ubyte *tb_table)
 
   generate_test_list(tb_size, entry_piece.num);
   if (!tb_table && !(tb_table = malloc(tb_size + 1))) {
-    printf("Out of memory.\n");
+    fprintf(stderr, "Out of memory.\n");
     exit(1);
   }
 
@@ -1193,7 +1193,7 @@ ubyte *init_permute_file(int *pcs, int file, ubyte *tb_table)
   generate_test_list(tb_size, entry_pawn.num);
 
   if (!tb_table && !(tb_table = malloc(tb_size + 1))) {
-    printf("Out of memory.\n");
+    fprintf(stderr, "Out of memory.\n");
     exit(1);
   }
 
diff --git a/src/probe.c b/src/probe.c
index 0a2dc1d..a7bff60 100644
--- a/src/probe.c
+++ b/src/probe.c
@@ -116,7 +116,7 @@ void add_to_hash(struct TBEntry *ptr, long64 key)
   while (i < HSHMAX && TB_hash[hshidx][i].ptr)
     i++;
   if (i == HSHMAX) {
-    printf("HSHMAX too low!\n");
+    fprintf(stderr, "HSHMAX too low!\n");
     exit(1);
   } else {
     TB_hash[hshidx][i].key = key;
@@ -180,13 +180,13 @@ static void init_tb(char *str)
   }
   if (pcs[WPAWN] + pcs[BPAWN] == 0) {
     if (TBnum_piece == TBMAX_PIECE) {
-      printf("TBMAX_PIECE limit too low!\n");
+      fprintf(stderr, "TBMAX_PIECE limit too low!\n");
       exit(1);
     }
     entry = (struct TBEntry *)&TB_piece[TBnum_piece++];
   } else {
     if (TBnum_pawn == TBMAX_PAWN) {
-      printf("TBMAX_PAWN limit too low!\n");
+      fprintf(stderr, "TBMAX_PAWN limit too low!\n");
       exit(1);
     }
     entry = (struct TBEntry *)&TB_pawn[TBnum_pawn++];
@@ -2126,7 +2126,7 @@ static void init_table(struct TBEntry *entry, long64 key)
   entry->data = map_file(file, 1, &dummy);
   ubyte *data = (ubyte *)entry->data;
   if (((uint32 *)data)[0] != WDL_MAGIC) {
-    printf("Corrupted table.\n");
+    fprintf(stderr, "Corrupted table.\n");
     exit(1);
   }
 
@@ -3030,7 +3030,7 @@ static __attribute__ ((noinline)) void probe_failed(int *pieces)
       if (pieces[j] == BKING - i)
 	str[k++] = pchr[i];
   str[k] = 0;
-  printf("Missing table: %s\n", str);
+  fprintf(stderr, "Missing table: %s\n", str);
   exit(1);
 }
 
diff --git a/src/reduce.c b/src/reduce.c
index af7672f..6cac980 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -20,16 +20,16 @@ void save_table(ubyte *table, char color)
   if (!lz4_buf) {
     lz4_buf = malloc(4 + LZ4_compressBound(COPYSIZE));
     if (!lz4_buf) {
-      printf("Out of memory.\n");
-      exit(0);
+      fprintf(stderr, "Out of memory.\n");
+      exit(1);
     }
   }
 
   sprintf(name, "%s.%c.%d", tablename, color, num_saves);
 
   if (!(F = fopen(name, "wb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   for (i = 0; i < 256; i++)
@@ -99,8 +99,8 @@ void reconstruct_table_pass(ubyte *table, char color, int k, ubyte *v)
   sprintf(name, "%s.%c.%d", tablename, color, k);
 
   if (!(F = fopen(name, "rb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
@@ -185,8 +185,10 @@ void verify_stats(ubyte *table, long64 *tot_stats, struct dtz_map *map)
       verify_ok = 0;
     }
 
-  if (!verify_ok)
+  if (!verify_ok) {
+    fprintf(stderr, "Verification of reconstructed table failed.\n");
     exit(1);
+  }
 }
 
 void reconstruct_table(ubyte *table, char color, struct dtz_map *map)
@@ -413,16 +415,16 @@ void store_table(ubyte *table, char color)
   if (!lz4_buf) {
     lz4_buf = malloc(4 + LZ4_compressBound(COPYSIZE));
     if (!lz4_buf) {
-      printf("Out of memory.\n");
-      exit(0);
+      fprintf(stderr, "Out of memory.\n");
+      exit(1);
     }
   }
 
   sprintf(name, "%s.%c", tablename, color);
 
   if (!(F = fopen(name, "wb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
@@ -448,8 +450,8 @@ void load_table(ubyte *table, char color)
   sprintf(name, "%s.%c", tablename, color);
 
   if (!(F = fopen(name, "rb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
diff --git a/src/reducep.c b/src/reducep.c
index f21d462..4684a58 100644
--- a/src/reducep.c
+++ b/src/reducep.c
@@ -29,16 +29,16 @@ void save_table(ubyte *table, char color, int local, long64 begin, long64 size)
   if (!lz4_buf) {
     lz4_buf = malloc(8 + LZ4_compressBound(COPYSIZE));
     if (!lz4_buf) {
-      printf("Out of memory.\n");
-      exit(0);
+      fprintf(stderr, "Out of memory.\n");
+      exit(1);
     }
   }
 
   if (local == num_saves) {
     sprintf(name, "%s.%c.%d", tablename, color, num_saves);
     if (!(F = fopen(name, "wb"))) {
-      printf("Could not open %s for writing.\n", name);
-      exit(-1);
+      fprintf(stderr, "Could not open %s for writing.\n", name);
+      exit(1);
     }
     tmp_table[num_saves][color == 'w' ? 0 : 1] = F;
   } else {
@@ -113,8 +113,8 @@ void reconstruct_table_pass(ubyte *table, char color, int k, ubyte *v)
   sprintf(name, "%s.%c.%d", tablename, color, k);
 
   if (!(F = fopen(name, "rb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
@@ -184,8 +184,10 @@ void verify_stats(ubyte *table, long64 *tot_stats, struct dtz_map *map)
       verify_ok = 0;
     }
 
-  if (!verify_ok)
+  if (!verify_ok) {
+    fprintf(stderr, "Verification of reconstructed table failed.\n");
     exit(1);
+  }
 }
 
 void reconstruct_table(ubyte *table, char color, struct dtz_map *map)
@@ -441,16 +443,16 @@ void store_table(ubyte *table, char color)
   if (!lz4_buf) {
     lz4_buf = malloc(8 + LZ4_compressBound(COPYSIZE));
     if (!lz4_buf) {
-      printf("Out of memory.\n");
-      exit(0);
+      fprintf(stderr, "Out of memory.\n");
+      exit(1);
     }
   }
 
   sprintf(name, "%s.%c", tablename, color);
 
   if (!(F = fopen(name, "wb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
@@ -476,8 +478,8 @@ void load_table(ubyte *table, char color)
   sprintf(name, "%s.%c", tablename, color);
 
   if (!(F = fopen(name, "rb"))) {
-    printf("Could not open %s for writing.\n", name);
-    exit(-1);
+    fprintf(stderr, "Could not open %s for writing.\n", name);
+    exit(1);
   }
 
   ubyte *ptr = table;
diff --git a/src/rtbver.c b/src/rtbver.c
index 1ac1e60..6f336aa 100644
--- a/src/rtbver.c
+++ b/src/rtbver.c
@@ -823,7 +823,7 @@ void load_wdl(struct thread_data *thread)
     if (unlikely(v2 > 4)) table[idx_p] = WDL_ERROR;
     else table[idx_p] = wdl_matrix[v2][v1_p];
 if(unlikely(table[idx_p]==WDL_ERROR))
-printf("WDL_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx_p, v2, v1_p);
+error("WDL_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx_p, v2, v1_p);
     v1_p = v1;
     idx_p = idx;
     idx2_p = idx2;
@@ -833,7 +833,7 @@ printf("WDL_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx_p, v2, v1_p);
   if (unlikely(v2 > 4)) table[idx_p] = WDL_ERROR;
   else table[idx_p] = wdl_matrix[v2][v1_p];
 if(unlikely(table[idx_p]==WDL_ERROR))
-printf("WDL_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx_p, v2, v1_p);
+error("WDL_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx_p, v2, v1_p);
 }
 #else
 void load_wdl(struct thread_data *thread)
@@ -1094,7 +1094,7 @@ void wdl_load_wdl(struct thread_data *thread)
     if (unlikely(v2 > 4)) table[idx] = W_ERROR;
     else table[idx] = w_wdl_matrix[v2][v1];
 if(unlikely(table[idx]==W_ERROR))
-printf("W_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx, v2, v1);
+error("W_ERROR: idx = %"PRIu64", v2 = %d, v1 = %d\n", idx, v2, v1);
   }
 }
 
diff --git a/src/stats.c b/src/stats.c
index 8e3c432..83c5095 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -81,7 +81,7 @@ static long64 find_val(ubyte *table, ubyte v)
   run_threaded(find_loop, work_g, 0);
 
   if (found_idx == 0xffffffffffffffffULL)
-    printf("find_val: not found!\n");
+    fprintf(stderr, "find_val: not found!\n");
 
   return found_idx;
 }
diff --git a/src/statsp.c b/src/statsp.c
index ab93eef..c46494b 100644
--- a/src/statsp.c
+++ b/src/statsp.c
@@ -83,7 +83,7 @@ long64 find_val(ubyte *table, ubyte v, long64 *work)
   run_threaded(find_loop, work, 0);
 
   if (found_idx == 0xffffffffffffffffULL)
-    printf("find_val: not found!\n");
+    fprintf(stderr, "find_val: not found!\n");
 
   return found_idx;
 }
diff --git a/src/tbcheck.c b/src/tbcheck.c
index c8010f2..629ae10 100644
--- a/src/tbcheck.c
+++ b/src/tbcheck.c
@@ -18,18 +18,18 @@ static void compare_checksums(char *file)
 
   FILE *F = fopen(file, "r");
   if (!F) {
-    printf("Could not open %s.\n", file);
+    fprintf(stderr, "Could not open %s.\n", file);
     return;
   }
   while (!feof(F)) {
     int num = fscanf(F, "%100[KQRBNP|v|rtbwz|.]: %32[0-9|a-f]\n", name, sum);
     if (num != 2 || strlen(sum) != 32) {
-      printf("Could not completely parse %s.\n", file);
+      fprintf(stderr, "Could not completely parse %s.\n", file);
       break;
     }
     FILE *G = fopen(name, "rb");
     if (!G) {
-      printf("Tablebase file %s not found.\n", name);
+      fprintf(stderr, "Tablebase file %s not found.\n", name);
     } else {
       fclose(G);
       print_checksum(name, sum2);
@@ -74,7 +74,7 @@ int main(int argc, char **argv)
   } while (val != EOF);
 
   if (optind >= argc) {
-    printf("No tablebase specified.\n");
+    fprintf(stderr, "No tablebase specified.\n");
     exit(0);
   }
 
diff --git a/src/tbgen.c b/src/tbgen.c
index a7955ec..0cc1927 100644
--- a/src/tbgen.c
+++ b/src/tbgen.c
@@ -568,8 +568,8 @@ int main(int argc, char **argv)
   } while (val != EOF);
 
   if (optind >= argc) {
-    printf("No tablebase specified.\n");
-    exit(0);
+    fprintf(stderr, "No tablebase specified.\n");
+    exit(1);
   }
   tablename = argv[optind];
 
@@ -618,23 +618,23 @@ int main(int argc, char **argv)
 
 #ifndef SUICIDE
   if (pcs[WKING] != 1 || pcs[BKING] != 1) {
-    printf("Need one white king and one black king.\n");
+    fprintf(stderr, "Need one white king and one black king.\n");
     exit(1);
   }
 
   if (numpcs < 3) {
-    printf("Need at least 3 pieces.\n");
+    fprintf(stderr, "Need at least 3 pieces.\n");
     exit(1);
   }
 #else
   if (numpcs < 2) {
-    printf("Need at least 2 pieces.\n");
+    fprintf(stderr, "Need at least 2 pieces.\n");
     exit(1);
   }
 #endif
 
   if (pcs[WPAWN] || pcs[BPAWN]) {
-    printf("Can't handle pawns.\n");
+    fprintf(stderr, "Can't handle pawns.\n");
     exit(1);
   }
 
diff --git a/src/tbgenp.c b/src/tbgenp.c
index 3228017..042b1eb 100644
--- a/src/tbgenp.c
+++ b/src/tbgenp.c
@@ -672,8 +672,8 @@ int main(int argc, char **argv)
   } while (val != EOF);
 
   if (optind >= argc) {
-    printf("No tablebase specified.\n");
-    exit(0);
+    fprintf(stderr, "No tablebase specified.\n");
+    exit(1);
   }
   tablename = argv[optind];
 
@@ -726,23 +726,23 @@ int main(int argc, char **argv)
 
 #ifndef SUICIDE
   if (pcs[WKING] != 1 || pcs[BKING] != 1) {
-    printf("Need one white king and one black king.\n");
+    fprintf(stderr, "Need one white king and one black king.\n");
     exit(1);
   }
 
   if (numpcs < 3) {
-    printf("Need at least 3 pawns or pieces.\n");
+    fprintf(stderr, "Need at least 3 pawns or pieces.\n");
     exit(1);
   }
 #else
   if (numpcs < 2) {
-    printf("Need at least 2 pawns or pieces.\n");
+    fprintf(stderr, "Need at least 2 pawns or pieces.\n");
     exit(1);
   }
 #endif
 
   if (numpawns == 0) {
-    printf("Expecting pawns.\n");
+    fprintf(stderr, "Expecting pawns.\n");
     exit(1);
   }
 
diff --git a/src/tbver.c b/src/tbver.c
index 35aa6b2..6477106 100644
--- a/src/tbver.c
+++ b/src/tbver.c
@@ -162,8 +162,8 @@ int main(int argc, char **argv)
   } while (val != EOF);
 
   if (optind >= argc) {
-    printf("No tablebase specified.\n");
-    exit(0);
+    fprintf(stderr, "No tablebase specified.\n");
+    exit(1);
   }
   tablename = argv[optind];
 
@@ -211,7 +211,7 @@ int main(int argc, char **argv)
   if (!color) exit(1);
 
   if (pcs[WPAWN] || pcs[BPAWN]) {
-    printf("Can't handle pawns.\n");
+    fprintf(stderr, "Can't handle pawns.\n");
     exit(1);
   }
 
diff --git a/src/tbverp.c b/src/tbverp.c
index f964af1..979820d 100644
--- a/src/tbverp.c
+++ b/src/tbverp.c
@@ -240,8 +240,8 @@ int main(int argc, char **argv)
   } while (val != EOF);
 
   if (optind >= argc) {
-    printf("No tablebase specified.\n");
-    exit(0);
+    fprintf(stderr, "No tablebase specified.\n");
+    exit(1);
   }
   tablename = argv[optind];
 
@@ -310,7 +310,7 @@ int main(int argc, char **argv)
   }
 
   if (numpawns == 0) {
-    printf("Expecting pawns.\n");
+    fprintf(stderr, "Expecting pawns.\n");
     exit(1);
   }
 
@@ -325,7 +325,7 @@ int main(int argc, char **argv)
   symmetric = (i == 8);
 
   if (symmetric) {
-    printf("Can't handle symmetric tables.\n");
+    fprintf(stderr, "Can't handle symmetric tables.\n");
     exit(1);
   }
 
diff --git a/src/threads.c b/src/threads.c
index d8d2dc2..0339ad4 100644
--- a/src/threads.c
+++ b/src/threads.c
@@ -142,7 +142,7 @@ void init_threads(int pawns)
     int rc = pthread_create(&threads[i], NULL, worker,
 				  (void *)&(thread_data[i]));
     if (rc) {
-      printf("ERROR: pthread_create() returned %d\n", rc);
+      fprintf(stderr, "ERROR: pthread_create() returned %d\n", rc);
       exit(1);
     }
   }
@@ -151,7 +151,7 @@ void init_threads(int pawns)
     start_event[i] = CreateEvent(NULL, FALSE, FALSE, NULL);
     stop_event[i] = CreateEvent(NULL, FALSE, FALSE, NULL);
     if (!start_event[i] || !stop_event[i]) {
-      printf("CreateEvent() failed.\n");
+      fprintf(stderr, "CreateEvent() failed.\n");
       exit(1);
     }
   }
@@ -159,7 +159,7 @@ void init_threads(int pawns)
     threads[i] = CreateThread(NULL, 0, worker, (void *)&(thread_data[i]),
 				  0, NULL);
     if (threads[i] == NULL) {
-      printf("CreateThread() failed.\n");
+      fprintf(stderr, "CreateThread() failed.\n");
       exit(1);
     }
   }
diff --git a/src/util.c b/src/util.c
index 8d2284a..77e339b 100644
--- a/src/util.c
+++ b/src/util.c
@@ -20,7 +20,7 @@ char *map_file(char *name, int shared, long64 *size)
   struct stat statbuf;
   int fd = open(name, O_RDONLY);
   if (fd < 0) {
-    printf("Could not open %s for reading.\n", name);
+    fprintf(stderr, "Could not open %s for reading.\n", name);
     exit(1);
   }
   fstat(fd, &statbuf);
@@ -32,7 +32,7 @@ char *map_file(char *name, int shared, long64 *size)
   char *data = (char *)mmap(NULL, statbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
 #endif
   if (data == (char *)(-1)) {
-    printf("Could not mmap() %s.\n", name);
+    fprintf(stderr, "Could not mmap() %s.\n", name);
     exit(1);
   }
   close(fd);
@@ -41,7 +41,7 @@ char *map_file(char *name, int shared, long64 *size)
   HANDLE h = CreateFile(name, GENERIC_READ, FILE_SHARE_READ, NULL,
 			  OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
   if (h == INVALID_HANDLE_VALUE) {
-    printf("Could not open %s for reading.\n", name);
+    fprintf(stderr, "Could not open %s for reading.\n", name);
     exit(1);
   }
   DWORD size_low, size_high;
@@ -50,12 +50,12 @@ char *map_file(char *name, int shared, long64 *size)
   HANDLE map = CreateFileMapping(h, NULL, PAGE_READONLY, size_high, size_low,
 				  NULL);
   if (map == NULL) {
-    printf("CreateFileMapping() failed.\n");
+    fprintf(stderr, "CreateFileMapping() failed.\n");
     exit(1);
   }
   char *data = (char *)MapViewOfFile(map, FILE_MAP_READ, 0, 0, 0);
   if (data == NULL) {
-    printf("MapViewOfFile() failed.\n");
+    fprintf(stderr, "MapViewOfFile() failed.\n");
     exit(1);
   }
   CloseHandle(h);
@@ -79,7 +79,7 @@ ubyte *alloc_aligned(long64 size, uintptr_t alignment)
 
   posix_memalign((void **)&ptr, alignment, size);
   if (ptr == NULL) {
-    printf("Could not allocate sufficient memory.\n");
+    fprintf(stderr, "Could not allocate sufficient memory.\n");
     exit(1);
   }
 
@@ -89,7 +89,7 @@ ubyte *alloc_aligned(long64 size, uintptr_t alignment)
 
   ptr = malloc(size + alignment - 1);
   if (ptr == NULL) {
-    printf("Could not allocate sufficient memory.\n");
+    fprintf(stderr, "Could not allocate sufficient memory.\n");
     exit(1);
   }
   ptr = (ubyte *)((uintptr_t)(ptr + alignment - 1) & ~(alignment - 1));
@@ -105,7 +105,7 @@ ubyte *alloc_huge(long64 size)
 
   posix_memalign((void **)&ptr, 2 * 1024 * 1024, size);
   if (ptr == NULL) {
-    printf("Could not allocate sufficient memory.\n");
+    fprintf(stderr, "Could not allocate sufficient memory.\n");
     exit(1);
   }
 #ifdef __linux__
@@ -118,7 +118,7 @@ ubyte *alloc_huge(long64 size)
 
   ptr = malloc(size);
   if (ptr == NULL) {
-    printf("Could not allocate sufficient memory.\n");
+    fprintf(stderr, "Could not allocate sufficient memory.\n");
     exit(1);
   }