diff --git a/src/config2setopts.c b/src/config2setopts.c
index 171ba6986a..9138b3b147 100644
--- a/src/config2setopts.c
+++ b/src/config2setopts.c
@@ -519,7 +519,7 @@ static CURLcode cookie_setopts(struct OperationConfig *config, CURL *curl)
                                 ISBLANK(cl->data[0]) ? "" : " ", cl->data);
       if(result) {
         warnf("skipped provided cookie, the cookie header "
-              "would go over %u bytes", MAX_COOKIE_LINE);
+              "would go over %d bytes", MAX_COOKIE_LINE);
         return result;
       }
     }
diff --git a/src/tool_getparam.c b/src/tool_getparam.c
index 30163561ea..176d3ebc38 100644
--- a/src/tool_getparam.c
+++ b/src/tool_getparam.c
@@ -2255,7 +2255,7 @@ static ParameterError opt_file(struct OperationConfig *config,
     break;
   case C_CONFIG: /* --config */
     if(--max_recursive < 0) {
-      errorf("Max config file recursion level reached (%u)",
+      errorf("Max config file recursion level reached (%d)",
              CONFIG_MAX_LEVELS);
       err = PARAM_BAD_USE;
     }
diff --git a/src/var.c b/src/var.c
index a149751d9f..79ff888dbb 100644
--- a/src/var.c
+++ b/src/var.c
@@ -394,7 +394,7 @@ ParameterError setvariable(const char *input)
     line++;
   nlen = line - name;
   if(!nlen || (nlen >= MAX_VAR_LEN)) {
-    warnf("Bad variable name length (%zd), skipping", nlen);
+    warnf("Bad variable name length (%zu), skipping", nlen);
     return PARAM_OK;
   }
   if(import) {
diff --git a/tests/libtest/cli_ws_data.c b/tests/libtest/cli_ws_data.c
index 856d41ba1f..80b007ec72 100644
--- a/tests/libtest/cli_ws_data.c
+++ b/tests/libtest/cli_ws_data.c
@@ -37,13 +37,13 @@ static CURLcode test_ws_data_m2_check_recv(const struct curl_ws_frame *frame,
   if(frame->flags & CURLWS_CLOSE) {
     curl_mfprintf(stderr, "recv_data: unexpected CLOSE frame from server, "
                   "got %zu bytes, offset=%zu, rflags %x\n",
-                  nread, r_offset, frame->flags);
+                  nread, r_offset, (unsigned int)frame->flags);
     return CURLE_RECV_ERROR;
   }
   if(!r_offset && !(frame->flags & CURLWS_BINARY)) {
     curl_mfprintf(stderr, "recv_data: wrong frame, got %zu bytes, offset=%zu, "
                   "rflags %x\n",
-                  nread, r_offset, frame->flags);
+                  nread, r_offset, (unsigned int)frame->flags);
     return CURLE_RECV_ERROR;
   }
   if(frame->offset != (curl_off_t)r_offset) {
diff --git a/tests/libtest/lib1558.c b/tests/libtest/lib1558.c
index 4077cb8eb1..3ac933092c 100644
--- a/tests/libtest/lib1558.c
+++ b/tests/libtest/lib1558.c
@@ -47,7 +47,7 @@ static CURLcode test_lib1558(const char *URL)
     goto test_cleanup;
   }
 
-  curl_mprintf("Protocol: %lx\n", protocol);
+  curl_mprintf("Protocol: %lx\n", (unsigned long)protocol);
 
   curl_easy_cleanup(curl);
   curl_global_cleanup();
diff --git a/tests/libtest/lib1560.c b/tests/libtest/lib1560.c
index 0e203dd96f..caff664720 100644
--- a/tests/libtest/lib1560.c
+++ b/tests/libtest/lib1560.c
@@ -1914,41 +1914,41 @@ static int get_nothing(void)
 
     rc = curl_url_get(u, CURLUPART_SCHEME, &p, 0);
     if(rc != CURLUE_NO_SCHEME)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_HOST, &p, 0);
     if(rc != CURLUE_NO_HOST)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_USER, &p, 0);
     if(rc != CURLUE_NO_USER)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_PASSWORD, &p, 0);
     if(rc != CURLUE_NO_PASSWORD)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_OPTIONS, &p, 0);
     if(rc != CURLUE_NO_OPTIONS)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_PATH, &p, 0);
     if(rc != CURLUE_OK)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
     else
       curl_free(p);
 
     rc = curl_url_get(u, CURLUPART_QUERY, &p, 0);
     if(rc != CURLUE_NO_QUERY)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_FRAGMENT, &p, 0);
     if(rc != CURLUE_NO_FRAGMENT)
-      curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+      curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
     rc = curl_url_get(u, CURLUPART_ZONEID, &p, 0);
     if(rc != CURLUE_NO_ZONEID)
-      curl_mfprintf(stderr, "unexpected return code %u on line %u\n", rc,
+      curl_mfprintf(stderr, "unexpected return code %d on line %d\n", rc,
                     __LINE__);
 
     curl_url_cleanup(u);
@@ -1981,17 +1981,17 @@ static int clear_url(void)
     for(i = 0; clear_url_list[i].in && !error; i++) {
       rc = curl_url_set(u, clear_url_list[i].part, clear_url_list[i].in, 0);
       if(rc != CURLUE_OK)
-        curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+        curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
       rc = curl_url_set(u, CURLUPART_URL, NULL, 0);
       if(rc != CURLUE_OK)
-        curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+        curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
 
       rc = curl_url_get(u, clear_url_list[i].part, &p, 0);
       if(rc != clear_url_list[i].ucode ||
          (clear_url_list[i].out && strcmp(p, clear_url_list[i].out) != 0)) {
 
-        curl_mfprintf(stderr, "unexpected return code line %u\n", __LINE__);
+        curl_mfprintf(stderr, "unexpected return code line %d\n", __LINE__);
         error++;
       }
       if(rc == CURLUE_OK)
@@ -2046,7 +2046,7 @@ static int huge(void)
     rc = curl_url_set(urlp, CURLUPART_URL, total, CURLU_NON_SUPPORT_SCHEME);
     if((!i && (rc != CURLUE_BAD_SCHEME)) ||
        (i && rc)) {
-      curl_mprintf("URL %u: failed to parse [%s]\n", i, total);
+      curl_mprintf("URL %d: failed to parse [%s]\n", i, total);
       error++;
     }
 
@@ -2054,7 +2054,7 @@ static int huge(void)
     if(!rc) {
       curl_url_get(urlp, part[i], &partp, 0);
       if(!partp || strcmp(partp, &bigpart[1 - (i == 4)])) {
-        curl_mprintf("URL %u part %u: failure\n", i, part[i]);
+        curl_mprintf("URL %d part %u: failure\n", i, part[i]);
         error++;
       }
       curl_free(partp);