diff --git a/util/random/rng.h b/util/random/rng.h
index d1355f8cac..89e0808deb 100644
--- a/util/random/rng.h
+++ b/util/random/rng.h
@@ -37,7 +37,7 @@ public:
 	MersenneTwister(uint32_t seed) : index_(0) {
 		mt_[0] = seed;
 		for (uint32_t i = 1; i < MT_SIZE; i++)
-			mt_[i] = (1812433253 * (mt_[i - 1] ^ (mt_[i - 1] >> 30)) + i);
+			mt_[i] = (1812433253UL * (mt_[i - 1] ^ (mt_[i - 1] >> 30)) + i);
 	}
 
 	uint32_t R32() {
@@ -45,8 +45,8 @@ public:
 			gen();
 		uint32_t y = mt_[index_];
 		y ^=  y >> 11;
-		y ^= (y <<  7) & 2636928640;
-		y ^= (y << 15) & 4022730752;
+		y ^= (y <<  7) & 2636928640UL;
+		y ^= (y << 15) & 4022730752UL;
 		y ^=  y >> 18;
 		index_ = (index_ + 1) % MT_SIZE;
 		return y;
@@ -64,7 +64,7 @@ private:
 		for(uint32_t i = 0; i < MT_SIZE; i++){
 			uint32_t y = (mt_[i] & 0x80000000) + (mt_[(i + 1) % MT_SIZE] & 0x80000000);
 			mt_[i] = mt_[(i + 397) % MT_SIZE] ^ (y >> 1);
-			if (y % 2) mt_[i] ^= 2567483615;
+			if (y % 2) mt_[i] ^= 2567483615UL;
 		}
 		return;
 	}