diff --git a/base/third_party/cityhash_v103/src/city_v103.cc b/base/third_party/cityhash_v103/src/city_v103.cc
index 4aa37301088b4..7866e6cee8187 100644
--- a/base/third_party/cityhash_v103/src/city_v103.cc
+++ b/base/third_party/cityhash_v103/src/city_v103.cc
@@ -117,7 +117,7 @@ static uint64 Rotate(uint64 val, int shift) {
 // Equivalent to Rotate(), but requires the second arg to be non-zero.
 // On x86-64, and probably others, it's possible for this to compile
 // to a single instruction if both args are already in registers.
-static uint64 RotateByAtLeast1(uint64 val, int shift) {
+static uint64 RotateByAtLeast1(uint64 val, size_t shift) {
   return (val >> shift) | (val << (64 - shift));
 }
 
@@ -140,11 +140,11 @@ static uint64 HashLen0to16(const char* s, size_t len) {
     return HashLen16(len + (a << 3), Fetch32(s + len - 4));
   }
   if (len > 0) {
-    uint8 a = s[0];
-    uint8 b = s[len >> 1];
-    uint8 c = s[len - 1];
+    uint8 a = static_cast<uint8>(s[0]);
+    uint8 b = static_cast<uint8>(s[len >> 1]);
+    uint8 c = static_cast<uint8>(s[len - 1]);
     uint32 y = static_cast<uint32>(a) + (static_cast<uint32>(b) << 8);
-    uint32 z = len + (static_cast<uint32>(c) << 2);
+    uint32 z = static_cast<uint32>(len) + (static_cast<uint32>(c) << 2);
     return ShiftMix(y * k2 ^ z * k3) * k2;
   }
   return k2;
@@ -266,15 +266,15 @@ static uint128 CityMurmur(const char* s, size_t len, uint128 seed) {
   uint64 b = Uint128High64(seed);
   uint64 c = 0;
   uint64 d = 0;
-  signed long l = len - 16;
-  if (l <= 0) {  // len <= 16
+  if (len <= 16) {
     a = ShiftMix(a * k1) * k1;
     c = b * k1 + HashLen0to16(s, len);
     d = ShiftMix(a + (len >= 8 ? Fetch64(s) : c));
-  } else {  // len > 16
+  } else {
     c = HashLen16(Fetch64(s + len - 8) + k1, a);
     d = HashLen16(b + len, c + Fetch64(s + len - 16));
     a += d;
+    // len > 16 here, so do...while is safe
     do {
       a ^= ShiftMix(Fetch64(s) * k1) * k1;
       a *= k1;
@@ -283,8 +283,8 @@ static uint128 CityMurmur(const char* s, size_t len, uint128 seed) {
       c *= k1;
       d ^= c;
       s += 16;
-      l -= 16;
-    } while (l > 0);
+      len -= 16;
+    } while (len > 16);
   }
   a = HashLen16(a, c);
   b = HashLen16(d, b);