diff --git a/logging.c b/logging.c
index e324c77c..d61038c9 100644
--- a/logging.c
+++ b/logging.c
@@ -344,7 +344,7 @@ void log_packet(LogContext *ctx, int direction, int type,
         /* If we're about to stop omitting, it's time to say how
          * much we omitted. */
         if ((blktype != PKTLOG_OMIT) && omitted) {
-            logprintf(ctx, "  (%d byte%s omitted)\r\n",
+            logprintf(ctx, "  (%zu byte%s omitted)\r\n",
                       omitted, (omitted==1?"":"s"));
             omitted = 0;
         }
@@ -387,7 +387,7 @@ void log_packet(LogContext *ctx, int direction, int type,
 
     /* Tidy up */
     if (omitted)
-        logprintf(ctx, "  (%d byte%s omitted)\r\n",
+        logprintf(ctx, "  (%zu byte%s omitted)\r\n",
                   omitted, (omitted==1?"":"s"));
     logflush(ctx);
 }
diff --git a/misc.c b/misc.c
index 610f0f3d..9ca15c8f 100644
--- a/misc.c
+++ b/misc.c
@@ -223,7 +223,7 @@ char *buildinfo(const char *newline)
 #else
     strbuf_catf(buf, ", emulating ");
 #endif
-    strbuf_catf(buf, "Visual Studio", newline);
+    strbuf_catf(buf, "Visual Studio");
 
 #if 0
     /*
diff --git a/pscp.c b/pscp.c
index 5f69e4c3..cadf7916 100644
--- a/pscp.c
+++ b/pscp.c
@@ -1789,7 +1789,7 @@ static void sink(const char *targ, const char *src)
                     with_stripctrl(santarg, act.name) {
                         tell_user(stderr, "warning: remote host sent a"
                                   " compound pathname '%s'", sanname);
-                        tell_user(stderr, "         renaming local",
+                        tell_user(stderr, "         renaming local"
                                   " file to '%s'", santarg);
                     }
                 }
diff --git a/ssh.c b/ssh.c
index 417d6c11..719d9e61 100644
--- a/ssh.c
+++ b/ssh.c
@@ -562,7 +562,7 @@ void ssh_deferred_abort_callback(void *vctx)
     Ssh *ssh = (Ssh *)vctx;
     char *msg = ssh->deferred_abort_message;
     ssh->deferred_abort_message = NULL;
-    ssh_sw_abort(ssh, msg);
+    ssh_sw_abort(ssh, "%s", msg);
     sfree(msg);
 }
 
diff --git a/ssh2connection.c b/ssh2connection.c
index 28054d43..a8c20f2d 100644
--- a/ssh2connection.c
+++ b/ssh2connection.c
@@ -750,7 +750,8 @@ static bool ssh2_connection_filter_queue(struct ssh2_connection_state *s)
                         "Received %s for channel %d with no outstanding "
                         "channel request",
                         ssh2_pkt_type(s->ppl.bpp->pls->kctx,
-                                      s->ppl.bpp->pls->actx, pktin->type));
+                                      s->ppl.bpp->pls->actx, pktin->type),
+                        c->localid);
                     return true;
                 }
                 ocr->handler(c, pktin, ocr->ctx);
diff --git a/sshhmac.c b/sshhmac.c
index 232d7680..29db9fbf 100644
--- a/sshhmac.c
+++ b/sshhmac.c
@@ -44,7 +44,7 @@ static ssh2_mac *hmac_new(const ssh2_macalg *alg, ssh_cipher *cipher)
     ctx->digest = snewn(ctx->hashalg->hlen, uint8_t);
 
     ctx->text_name = strbuf_new();
-    strbuf_catf(ctx->text_name, "HMAC-%s",
+    strbuf_catf(ctx->text_name, "HMAC-%s%s",
                 ctx->hashalg->text_basename, extra->suffix);
     if (extra->annotation || ctx->hashalg->annotation) {
         strbuf_catf(ctx->text_name, " (");
diff --git a/sshrsa.c b/sshrsa.c
index 81522aa8..504a73e7 100644
--- a/sshrsa.c
+++ b/sshrsa.c
@@ -296,7 +296,7 @@ char *rsa_ssh1_fingerprint(RSAKey *key)
     ssh_hash_final(hash, digest);
 
     out = strbuf_new();
-    strbuf_catf(out, "%d ", mp_get_nbits(key->modulus));
+    strbuf_catf(out, "%zu ", mp_get_nbits(key->modulus));
     for (i = 0; i < 16; i++)
         strbuf_catf(out, "%s%02x", i ? ":" : "", digest[i]);
     if (key->comment)
diff --git a/sshshare.c b/sshshare.c
index 98071d8e..573114cd 100644
--- a/sshshare.c
+++ b/sshshare.c
@@ -1794,8 +1794,9 @@ static void share_receive(Plug *plug, int urgent, const char *data, size_t len)
     }
     if (cs->recvlen > 0 && cs->recvbuf[cs->recvlen-1] == '\015')
         cs->recvlen--;                 /* trim off \r before \n */
+    ptrlen verstring = make_ptrlen(cs->recvbuf, cs->recvlen);
     log_downstream(cs, "Downstream version string: %.*s",
-                   cs->recvlen, cs->recvbuf);
+                   PTRLEN_PRINTF(verstring));
     cs->got_verstring = true;
 
     /*