diff --git a/src/mic/mic.cxx b/src/mic/mic.cxx
index 970c7163..9928335a 100644
--- a/src/mic/mic.cxx
+++ b/src/mic/mic.cxx
@@ -100,7 +100,7 @@ Microphone::findThreshold (thresholdContext* ctx, unsigned int threshold,
 
 void
 Microphone::printGraph (thresholdContext* ctx) {
-    for (int i = 0; i < ctx->runningAverage; i++)
+    for (unsigned int i = 0; i < ctx->runningAverage; i++)
         std::cout << ".";
     std::cout << std::endl;
 }
diff --git a/src/mic/mic.hpp b/src/mic/mic.hpp
index f54147dc..3aeafbb1 100644
--- a/src/mic/mic.hpp
+++ b/src/mic/mic.hpp
@@ -29,7 +29,7 @@
 
 struct thresholdContext {
     long averageReading;
-    long runningAverage;
+    unsigned long runningAverage;
     int averagedOver;
 };