diff --git a/src/tool_setopt.c b/src/tool_setopt.c
index 6dbf8baa4c..2174571ad4 100644
--- a/src/tool_setopt.c
+++ b/src/tool_setopt.c
@@ -226,8 +226,10 @@ static char *c_escape(const char *str, curl_off_t len)
     result = curlx_dyn_addn(&escaped, str, s - str);
 
   if(!result)
-    (void)!curlx_dyn_addn(&escaped, "...", cutoff);
+    result = curlx_dyn_addn(&escaped, "...", cutoff);
 
+  if(result)
+    return NULL;
   return curlx_dyn_ptr(&escaped);
 }
 
diff --git a/tests/server/util.c b/tests/server/util.c
index 9fc7952f84..dd4e9bacdb 100644
--- a/tests/server/util.c
+++ b/tests/server/util.c
@@ -321,12 +321,14 @@ static HWND hidden_main_window = NULL;
  * Hence, do not call 'logmsg()', and instead use 'open/write/close' to
  * log errors.
  */
+static size_t useless; /* to silence variable 'rc' set but not used */
 static void exit_signal_handler(int signum)
 {
   int old_errno = errno;
+  size_t rc = 0;
   if(!serverlogfile) {
     static const char msg[] = "exit_signal_handler: serverlogfile not set\n";
-    (void)!write(STDERR_FILENO, msg, sizeof(msg) - 1);
+    rc = write(STDERR_FILENO, msg, sizeof(msg) - 1);
   }
   else {
     int fd = -1;
@@ -340,14 +342,14 @@ static void exit_signal_handler(int signum)
     if(fd != -1) {
 #endif
       static const char msg[] = "exit_signal_handler: called\n";
-      (void)!write(fd, msg, sizeof(msg) - 1);
+      rc = write(fd, msg, sizeof(msg) - 1);
       curlx_close(fd);
     }
     else {
       static const char msg[] = "exit_signal_handler: failed opening ";
-      (void)!write(STDERR_FILENO, msg, sizeof(msg) - 1);
-      (void)!write(STDERR_FILENO, serverlogfile, strlen(serverlogfile));
-      (void)!write(STDERR_FILENO, "\n", 1);
+      rc = write(STDERR_FILENO, msg, sizeof(msg) - 1);
+      rc += write(STDERR_FILENO, serverlogfile, strlen(serverlogfile));
+      rc += write(STDERR_FILENO, "\n", 1);
     }
   }
   if(got_exit_signal == 0) {
@@ -358,6 +360,7 @@ static void exit_signal_handler(int signum)
       (void)SetEvent(exit_event);
 #endif
   }
+  useless = rc;
   (void)signal(signum, exit_signal_handler);
   errno = old_errno;
 }