diff --git a/tools/mouse-dpi-tool.c b/tools/mouse-dpi-tool.c
index 7f0e7be..905fb32 100644
--- a/tools/mouse-dpi-tool.c
+++ b/tools/mouse-dpi-tool.c
@@ -65,7 +65,7 @@ tv2us(const struct timeval *tv)
 }
 
 static inline double
-get_frequency(double last, double current)
+get_frequency(uint64_t last, uint64_t current)
 {
 	return 1000000.0/(current - last);
 }