diff --git a/f3read.c b/f3read.c
index 065a970..7537b2e 100644
--- a/f3read.c
+++ b/f3read.c
@@ -192,7 +192,7 @@ static ssize_t read_all(int fd, char *buf, size_t count)
 }
 
 static ssize_t check_chunk(int fd, uint64_t *p_expected_offset,
-	size_t chunk_size, struct file_stats *stats)
+	uint64_t chunk_size, struct file_stats *stats)
 {
 	char buf[MAX_BUFFER_SIZE];
 	ssize_t tot_bytes_read = 0;
diff --git a/f3write.c b/f3write.c
index b7e1a4a..20e30dc 100644
--- a/f3write.c
+++ b/f3write.c
@@ -203,7 +203,7 @@ static int create_and_fill_file(const char *path, long number, size_t size,
 	remaining = size;
 	start_measurement(fw);
 	while (remaining > 0) {
-		size_t write_size = get_rem_chunk_size(fw);
+		uint64_t write_size = get_rem_chunk_size(fw);
 		if (write_size > remaining)
 			write_size = remaining;
 		saved_errno = write_chunk(fd, write_size, &offset);
diff --git a/libflow.c b/libflow.c
index 7177c35..89ac5cf 100644
--- a/libflow.c
+++ b/libflow.c
@@ -244,7 +244,7 @@ static inline uint64_t diff_timeval_us(const struct timeval *t1,
 		t2->tv_usec - t1->tv_usec;
 }
 
-int measure(int fd, struct flow *fw, ssize_t processed)
+int measure(int fd, struct flow *fw, long processed)
 {
 	ldiv_t result = ldiv(processed, fw->block_size);
 	struct timeval t2;
diff --git a/libflow.h b/libflow.h
index cc3ca98..8dee7d9 100644
--- a/libflow.h
+++ b/libflow.h
@@ -63,7 +63,7 @@ void init_flow(struct flow *fw, uint64_t total_size,
 	flow_func_flush_chunk_t func_flush_chunk);
 
 void start_measurement(struct flow *fw);
-int measure(int fd, struct flow *fw, ssize_t processed);
+int measure(int fd, struct flow *fw, long processed);
 int end_measurement(int fd, struct flow *fw);
 
 static inline int has_enough_measurements(const struct flow *fw)
@@ -84,12 +84,10 @@ static inline double get_avg_speed(struct flow *fw)
 	return get_avg_speed_given_time(fw, fw->measured_time_ms);
 }
 
-static inline size_t get_rem_chunk_size(struct flow *fw)
+static inline uint64_t get_rem_chunk_size(struct flow *fw)
 {
-	ssize_t ret = (fw->blocks_per_delay - fw->processed_blocks) *
-		fw->block_size;
-	assert(ret > 0);
-	return ret;
+	assert(fw->blocks_per_delay > fw->processed_blocks);
+	return (fw->blocks_per_delay - fw->processed_blocks) * fw->block_size;
 }
 
 #define MAX_BUFFER_SIZE	(1<<21)	/* 2MB */