diff --git a/programs/util.c b/programs/util.c
index cdfda1ca0..e7acc6cbb 100644
--- a/programs/util.c
+++ b/programs/util.c
@@ -121,7 +121,7 @@ int UTIL_requireUserConfirmation(const char* prompt, const char* abortMsg,
 *  Functions
 ***************************************/
 
-char* humanSize(size_t size, char* str) {
+char* humanSize(unsigned long size, char* str) {
 	if (size > 1125899906842624L) {
 		snprintf(str, 7, "%.1fP", (float)size / 1125899906842624L);
 	} else if (size > 1099511627776L) {
diff --git a/programs/util.h b/programs/util.h
index 8ac930d8c..21e93d7d7 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -122,7 +122,7 @@ int UTIL_requireUserConfirmation(const char* prompt, const char* abortMsg, const
 #define STRDUP(s) strdup(s)
 #endif
 
-char* humanSize(size_t size, char* str);
+char* humanSize(unsigned long size, char* str);
 
 /**
  * Calls platform's equivalent of stat() on filename and writes info to statbuf.