diff --git a/src/rpcmining.cpp b/src/rpcmining.cpp
index cc78db76e..2d6b84d55 100644
--- a/src/rpcmining.cpp
+++ b/src/rpcmining.cpp
@@ -12,7 +12,8 @@
 using namespace json_spirit;
 using namespace std;
 
-static const int kLookupSpanMod = 240;
+// Number of blocks between difficulty changes
+static const int kDifficultyChangeInterval = 240;
 
 // Return average network hashes per second based on the last 'lookup' blocks,
 // or from the last difficulty change if 'lookup' is nonpositive.
@@ -28,7 +29,7 @@ Value GetNetworkHashPS(int lookup, int height) {
 
     // If lookup is -1, then use blocks since last difficulty change.
     if (lookup <= 0)
-        lookup = pb->nHeight % kLookupSpanMod + 1;
+        lookup = pb->nHeight % kDifficultyChangeInterval + 1;
 
     // If lookup is larger than chain, then set it to chain length.
     if (lookup > pb->nHeight)