diff --git a/libethereum/BlockChain.cpp b/libethereum/BlockChain.cpp
index 226b7aa06..e7188c238 100644
--- a/libethereum/BlockChain.cpp
+++ b/libethereum/BlockChain.cpp
@@ -924,8 +924,8 @@ void BlockChain::checkConsistency()
 	delete it;
 }
 
-static inline unsigned upow(unsigned a, unsigned b) { while (b-- > 0) a *= a; return a; }
-static inline unsigned ceilDiv(unsigned n, unsigned d) { return n / (n + d - 1); }
+static inline unsigned upow(unsigned a, unsigned b) { if (!b) return 1; while (--b > 0) a *= a; return a; }
+static inline unsigned ceilDiv(unsigned n, unsigned d) { return (n + d - 1) / d; }
 //static inline unsigned floorDivPow(unsigned n, unsigned a, unsigned b) { return n / upow(a, b); }
 //static inline unsigned ceilDivPow(unsigned n, unsigned a, unsigned b) { return ceilDiv(n, upow(a, b)); }