diff --git a/ares_init.c b/ares_init.c
index 442f8f54..eb1719ab 100644
--- a/ares_init.c
+++ b/ares_init.c
@@ -129,8 +129,12 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
   if (env)
     curl_memdebug(env);
   env = getenv("CARES_MEMLIMIT");
-  if (env)
-    curl_memlimit(atoi(env));
+  if (env) {
+    char *endptr;
+    long num = strtol(env, &endptr, 10);
+    if((endptr != env) && (endptr == env + strlen(env)) && (num > 0))
+      curl_memlimit(num);
+  }
 #endif
 
   if (ares_library_initialized() != ARES_SUCCESS)
@@ -1396,13 +1400,13 @@ static int set_options(ares_channel channel, const char *str)
         q++;
       val = try_option(p, q, "ndots:");
       if (val && channel->ndots == -1)
-        channel->ndots = atoi(val);
+        channel->ndots = (int)strtol(val, NULL, 10);
       val = try_option(p, q, "retrans:");
       if (val && channel->timeout == -1)
-        channel->timeout = atoi(val);
+        channel->timeout = (int)strtol(val, NULL, 10);
       val = try_option(p, q, "retry:");
       if (val && channel->tries == -1)
-        channel->tries = atoi(val);
+        channel->tries = (int)strtol(val, NULL, 10);
       val = try_option(p, q, "rotate");
       if (val && channel->rotate == -1)
         channel->rotate = 1;
diff --git a/ares_options.c b/ares_options.c
index 7b957a55..70280526 100644
--- a/ares_options.c
+++ b/ares_options.c
@@ -139,7 +139,7 @@ int ares_set_servers_csv(ares_channel channel,
   char* csv = NULL;
   char* ptr;
   char* start_host;
-  int port;
+  long port;
   bool found_port;
   int rv = ARES_SUCCESS;
   struct ares_addr_node *servers = NULL;
@@ -188,7 +188,7 @@ int ares_set_servers_csv(ares_channel channel,
       if ((pp != start_host) && ((pp + 1) < ptr)) {
         /* Found it. */
         found_port = true;
-        port = atoi(pp + 1);
+        port = strtol(pp + 1, NULL, 10);
         *pp = 0; /* null terminate host */
       }
       /* resolve host, try ipv4 first, rslt is in network byte order */