diff --git a/fmtx.c b/fmtx.c
index dd250b6..c0fd4a0 100644
--- a/fmtx.c
+++ b/fmtx.c
@@ -60,11 +60,11 @@ const TCHAR *fmtx_timestamp(int64_t n, unsigned int flags)
   {
   default:
   case FMTX_TS_DISPLAY_90kHz_RAW:
-    _stprintf(buf, _T("%") I64FMT _T("dt"), n27 / 300LL);
+    _sntprintf(buf, FMTX_BUFFER_SIZE, _T("%") I64FMT _T("dt"), n27 / 300LL);
     break;
 
   case FMTX_TS_DISPLAY_27MHz_RAW:
-    _stprintf(buf, _T("%") I64FMT _T("d:%03dt"), n27 / 300LL, frac_27MHz(n27));
+    _sntprintf(buf, FMTX_BUFFER_SIZE, _T("%") I64FMT _T("d:%03dt"), n27 / 300LL, frac_27MHz(n27));
     break;
 
   case FMTX_TS_DISPLAY_90kHz_32BIT:
@@ -73,13 +73,13 @@ const TCHAR *fmtx_timestamp(int64_t n, unsigned int flags)
       TCHAR * p = buf;
       if (n90 < 0)
         *p++ = _T('-');
-      _stprintf(p, _T("%ut"), (unsigned int)(n90 < 0 ? -n90 : n90));
+      _sntprintf(p, FMTX_BUFFER_SIZE, _T("%ut"), (unsigned int)(n90 < 0 ? -n90 : n90));
       break;
     }
 
   case FMTX_TS_DISPLAY_ms:
     // No timestamp when converted into ms should exceed 32bits
-    _stprintf(buf, _T("%dms"), (int)(n27 / 27000LL));
+    _sntprintf(buf, FMTX_BUFFER_SIZE, _T("%dms"), (int)(n27 / 27000LL));
     break;
 
   case FMTX_TS_DISPLAY_HMS:
@@ -93,7 +93,7 @@ const TCHAR *fmtx_timestamp(int64_t n, unsigned int flags)
       a27 /= I64K(60);
       m = (unsigned int)(a27 % I64K(60));
       h = (unsigned int)(a27 / I64K(60));
-      _stprintf(buf, _T("%s%u:%02u:%02u.%04u"), n27 < 0 ? _T("-") : _T(""), h, m, s, f/1000);
+      _sntprintf(buf, FMTX_BUFFER_SIZE, _T("%s%u:%02u:%02u.%04u"), n27 < 0 ? _T("-") : _T(""), h, m, s, f/1000);
       break;
     }
 
diff --git a/fmtx.h b/fmtx.h
index 8ee0cb4..0b4d23d 100644
--- a/fmtx.h
+++ b/fmtx.h
@@ -39,6 +39,7 @@ typedef char TCHAR;
 #define I64FMT "ll"
 #define I64K(x) x##LL
 #define _stprintf sprintf
+#define _sntprintf snprintf
 #define _tcscmp strcmp
 #endif
 
diff --git a/misc.c b/misc.c
index 1045ea9..4595be5 100644
--- a/misc.c
+++ b/misc.c
@@ -1476,7 +1476,7 @@ const char *ipv4_addr_to_string(const uint32_t addr)
 {
   static char buf[64];
 
-  sprintf(buf, "%d.%d.%d.%d", 
+  snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
 	  (addr >> 24)&0xff,
 	  (addr >> 16)&0xff,
 	  (addr >> 8)&0xff,
diff --git a/pcapreport.c b/pcapreport.c
index 882a836..77bb5cd 100644
--- a/pcapreport.c
+++ b/pcapreport.c
@@ -784,7 +784,7 @@ stream_merge_vlan_info(pcapreport_stream_t * const st, const ethernet_packet_t *
 }
 
 static char *
-vlan_name(const char * prefix, const pcapreport_stream_t * const st, char * const buf)
+vlan_name(const char * prefix, const pcapreport_stream_t * const st, const size_t blen, char * const buf)
 {
   if (st->vlan_count == 0)
   {
@@ -795,14 +795,17 @@ vlan_name(const char * prefix, const pcapreport_stream_t * const st, char * cons
     int i;
     size_t n = strlen(prefix);
     char * p = buf;
+    char * const eob = buf + blen;
+
     memcpy(p, prefix, n);
     p += n;
-    for (i = 0; i < st->vlan_count; ++i)
+
+    for (i = 0; i < st->vlan_count && eob - p > 2; ++i)
     {
       const pcapreport_vlan_info_t * const vi = st->vlans + i;
       if (i != 0)
         *p++ = '.';
-      p += sprintf(p, "%d", vi->vid);
+      p += snprintf(p, eob - p, "%d", vi->vid);
     }
   }
   return buf;
@@ -842,8 +845,8 @@ stream_create(pcapreport_ctx_t * const ctx,
     // that name!
     if (ctx->filter_dest_addr == 0 || ctx->filter_dest_port == 0)
     {
-      sprintf(st->output_name + len, "%s_%u.%u.%u.%u_%u.ts",
-        vlan_name("_V", st, pbuf),
+      snprintf(st->output_name + len, 64, "%s_%u.%u.%u.%u_%u.ts",
+        vlan_name("_V", st, sizeof(pbuf), pbuf),
         dest_addr >> 24, (dest_addr >> 16) & 0xff,
         (dest_addr >> 8) & 0xff, dest_addr & 0xff,
         dest_port);
@@ -860,8 +863,8 @@ stream_create(pcapreport_ctx_t * const ctx,
 
     if (ctx->filter_dest_addr == 0 || ctx->filter_dest_port == 0)
     {
-      sprintf(name + len, "%s_%u.%u.%u.%u_%u.csv",
-        vlan_name("_V", st, pbuf),
+      snprintf(name + len, 64, "%s_%u.%u.%u.%u_%u.csv",
+        vlan_name("_V", st, sizeof(pbuf), pbuf),
         dest_addr >> 24, (dest_addr >> 16) & 0xff,
         (dest_addr >> 8) & 0xff, dest_addr & 0xff,
         dest_port);
@@ -875,19 +878,20 @@ stream_create(pcapreport_ctx_t * const ctx,
 }
 
 static char *
-map_to_string(unsigned int n, char * const buf)
+map_to_string(unsigned int n, const size_t blen, char * const buf)
 {
   int i = 0;
   char * p = buf;
+  char * const eob = buf + blen;
   int first = TRUE;
 
-  while (n != 0)
+  while (n != 0 && eob - p > 2)
   {
     if ((n & 1) != 0)
     {
       if (!first)
         *p++ = ',';
-      p += sprintf(p, "%d", i);
+      p += snprintf(p, eob - p, "%d", i);
       first = FALSE;
     }
     n >>= 1;
@@ -907,7 +911,7 @@ stream_analysis(const pcapreport_ctx_t * const ctx, const pcapreport_stream_t *
 
   fprint_msg("Stream %d: Dest:%s %u.%u.%u.%u:%u\n",
     st->stream_no,
-    vlan_name(" VLAN:", st, pbuf),
+    vlan_name(" VLAN:", st, sizeof(pbuf), pbuf),
     dest_addr >> 24, (dest_addr >> 16) & 0xff,
     (dest_addr >> 8) & 0xff, dest_addr & 0xff,
     st->output_dest_port);
@@ -921,7 +925,7 @@ stream_analysis(const pcapreport_ctx_t * const ctx, const pcapreport_stream_t *
       char pbuf1[64], pbuf2[64];
 
       fprint_msg("  VLAN %d: cfi:[%s], pcp[%s]\n", vi->vid,
-        map_to_string(vi->cfimap, pbuf1), map_to_string(vi->pcpmap, pbuf2));
+        map_to_string(vi->cfimap, sizeof(pbuf1), pbuf1), map_to_string(vi->pcpmap, sizeof(pbuf2), pbuf2));
     }
   }
 
diff --git a/ts.c b/ts.c
index eaae21b..7c23da3 100644
--- a/ts.c
+++ b/ts.c
@@ -2616,7 +2616,7 @@ extern int print_descriptors(int    is_msg,
       default:
         {
           char    temp_c[50]; // twice as much as I need...
-          sprintf(temp_c, "%s (%d)",
+          snprintf(temp_c, sizeof(temp_c), "%s (%d)",
             tag < sizeof(descriptor_names)/sizeof(descriptor_names[0]) ?
                 descriptor_names[tag] :
               tag < 64 ? "Reserved" : "User Private",