diff --git a/qmemman/meminfo-writer.c b/qmemman/meminfo-writer.c
index c70fd43..8569273 100644
--- a/qmemman/meminfo-writer.c
+++ b/qmemman/meminfo-writer.c
@@ -7,7 +7,7 @@
 #include <string.h>
 #include <signal.h>
 
-unsigned long prev_used_mem;
+long prev_used_mem;
 int used_mem_change_threshold;
 int delay;
 int usr1_received;
@@ -27,7 +27,7 @@ const char *parse(const char *buf)
 
 	while (nitems != (1<<6)-1 || !*ptr) {
 		ret = sscanf(ptr, "%*s %d kB\n%n", &val, &len);
-		if (ret < 1 || len < sizeof (unsigned long long)) {
+		if (ret < 1 || len < (int)sizeof (unsigned long long)) {
 			ptr += len;
 			continue;
 		}
@@ -95,7 +95,7 @@ void send_to_qmemman(struct xs_handle *xs, const char *data)
 	}
 }
 
-void usr1_handler(int sig) {
+void usr1_handler(int sig __attribute__((__unused__))) {
 	usr1_received = 1;
 }
 
diff --git a/qrexec-lib/libqubes-rpc-filecopy.h b/qrexec-lib/libqubes-rpc-filecopy.h
index d735f86..d566345 100644
--- a/qrexec-lib/libqubes-rpc-filecopy.h
+++ b/qrexec-lib/libqubes-rpc-filecopy.h
@@ -64,7 +64,7 @@ typedef void (notify_progress_t)(int, int);
 void register_notify_progress(notify_progress_t *func);
 int copy_file(int outfd, int infd, long long size, unsigned long *crc32);
 const char *copy_file_status_to_str(int status);
-void set_size_limit(long long new_bytes_limit, long long new_files_limit);
+void set_size_limit(unsigned long long new_bytes_limit, unsigned long long new_files_limit);
 void set_verbose(int value);
 int write_all(int fd, const void *buf, int size);
 int read_all(int fd, void *buf, int size);
diff --git a/qrexec-lib/unpack.c b/qrexec-lib/unpack.c
index ca52c9c..d7787d1 100644
--- a/qrexec-lib/unpack.c
+++ b/qrexec-lib/unpack.c
@@ -13,12 +13,14 @@
 #include "crc32.h"
 
 char untrusted_namebuf[MAX_PATH_LENGTH];
-long long bytes_limit = 0;
-long long files_limit = 0;
-long long total_bytes = 0;
-long long total_files = 0;
+unsigned long long bytes_limit = 0;
+unsigned long long files_limit = 0;
+unsigned long long total_bytes = 0;
+unsigned long long total_files = 0;
 int verbose = 0;
 
+void send_status_and_crc(int code, const char *last_filename);
+
 void do_exit(int code, const char *last_filename)
 {
 	close(0);
@@ -26,11 +28,8 @@ void do_exit(int code, const char *last_filename)
 	exit(code);
 }
 
-void set_size_limit(long long new_bytes_limit, long long new_files_limit)
+void set_size_limit(unsigned long long new_bytes_limit, unsigned long long new_files_limit)
 {
-	if (new_bytes_limit < 0 || new_files_limit < 0) {
-		do_exit(EINVAL, "");
-	}
 	bytes_limit = new_bytes_limit;
 	files_limit = new_files_limit;
 }