diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
index cf665a4e8..7a73ef527 100644
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -1563,7 +1563,7 @@ ngx_escape_uri(u_char *dst, u_char *src, size_t size, ngx_uint_t type)
         n = 0;
 
         while (size) {
-            if (escape[*src >> 5] & (1 << (*src & 0x1f))) {
+            if (escape[*src >> 5] & (1U << (*src & 0x1f))) {
                 n++;
             }
             src++;
@@ -1574,7 +1574,7 @@ ngx_escape_uri(u_char *dst, u_char *src, size_t size, ngx_uint_t type)
     }
 
     while (size) {
-        if (escape[*src >> 5] & (1 << (*src & 0x1f))) {
+        if (escape[*src >> 5] & (1U << (*src & 0x1f))) {
             *dst++ = '%';
             *dst++ = hex[*src >> 4];
             *dst++ = hex[*src & 0xf];
diff --git a/src/http/modules/ngx_http_log_module.c b/src/http/modules/ngx_http_log_module.c
index df9424f83..c42fb08ed 100644
--- a/src/http/modules/ngx_http_log_module.c
+++ b/src/http/modules/ngx_http_log_module.c
@@ -1000,7 +1000,7 @@ ngx_http_log_escape(u_char *dst, u_char *src, size_t size)
         n = 0;
 
         while (size) {
-            if (escape[*src >> 5] & (1 << (*src & 0x1f))) {
+            if (escape[*src >> 5] & (1U << (*src & 0x1f))) {
                 n++;
             }
             src++;
@@ -1011,7 +1011,7 @@ ngx_http_log_escape(u_char *dst, u_char *src, size_t size)
     }
 
     while (size) {
-        if (escape[*src >> 5] & (1 << (*src & 0x1f))) {
+        if (escape[*src >> 5] & (1U << (*src & 0x1f))) {
             *dst++ = '\\';
             *dst++ = 'x';
             *dst++ = hex[*src >> 4];
diff --git a/src/http/modules/ngx_http_userid_filter_module.c b/src/http/modules/ngx_http_userid_filter_module.c
index 1487c091e..0dbacba08 100644
--- a/src/http/modules/ngx_http_userid_filter_module.c
+++ b/src/http/modules/ngx_http_userid_filter_module.c
@@ -836,7 +836,7 @@ ngx_http_userid_init_worker(ngx_cycle_t *cycle)
     ngx_gettimeofday(&tp);
 
     /* use the most significant usec part that fits to 16 bits */
-    start_value = ((tp.tv_usec / 20) << 16) | ngx_pid;
+    start_value = (((uint32_t) tp.tv_usec / 20) << 16) | ngx_pid;
 
     return NGX_OK;
 }
diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
index 59aa1fea9..bd6c9c9b5 100644
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -481,7 +481,7 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
         /* check "/.", "//", "%", and "\" (Win32) in URI */
         case sw_after_slash_in_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 state = sw_check_uri;
                 break;
             }
@@ -540,7 +540,7 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
         /* check "/", "%" and "\" (Win32) in URI */
         case sw_check_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 break;
             }
 
@@ -626,7 +626,7 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
         /* URI */
         case sw_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 break;
             }
 
@@ -1131,7 +1131,7 @@ ngx_http_parse_uri(ngx_http_request_t *r)
         /* check "/.", "//", "%", and "\" (Win32) in URI */
         case sw_after_slash_in_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 state = sw_check_uri;
                 break;
             }
@@ -1179,7 +1179,7 @@ ngx_http_parse_uri(ngx_http_request_t *r)
         /* check "/", "%" and "\" (Win32) in URI */
         case sw_check_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 break;
             }
 
@@ -1228,7 +1228,7 @@ ngx_http_parse_uri(ngx_http_request_t *r)
         /* URI */
         case sw_uri:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 break;
             }
 
@@ -1289,7 +1289,7 @@ ngx_http_parse_complex_uri(ngx_http_request_t *r, ngx_uint_t merge_slashes)
 
         case sw_usual:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 *u++ = ch;
                 ch = *p++;
                 break;
@@ -1358,7 +1358,7 @@ ngx_http_parse_complex_uri(ngx_http_request_t *r, ngx_uint_t merge_slashes)
 
         case sw_slash:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 state = sw_usual;
                 *u++ = ch;
                 ch = *p++;
@@ -1401,7 +1401,7 @@ ngx_http_parse_complex_uri(ngx_http_request_t *r, ngx_uint_t merge_slashes)
 
         case sw_dot:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 state = sw_usual;
                 *u++ = ch;
                 ch = *p++;
@@ -1442,7 +1442,7 @@ ngx_http_parse_complex_uri(ngx_http_request_t *r, ngx_uint_t merge_slashes)
 
         case sw_dot_dot:
 
-            if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+            if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
                 state = sw_usual;
                 *u++ = ch;
                 ch = *p++;
@@ -1836,7 +1836,7 @@ ngx_http_parse_unsafe_uri(ngx_http_request_t *r, ngx_str_t *uri,
             continue;
         }
 
-        if (usual[ch >> 5] & (1 << (ch & 0x1f))) {
+        if (usual[ch >> 5] & (1U << (ch & 0x1f))) {
             continue;
         }