diff --git a/src/lib/system/gnuc/armv6j/Unix.Mod b/src/lib/system/gnuc/armv6j/Unix.Mod
index 19d1c019..9e46278e 100644
--- a/src/lib/system/gnuc/armv6j/Unix.Mod
+++ b/src/lib/system/gnuc/armv6j/Unix.Mod
@@ -254,7 +254,7 @@ TYPE
   PROCEDURE -Select*(width: LONGINT; VAR readfds, writefds, exceptfds: FdSet; VAR timeout: Timeval): LONGINT
     "select(width, readfds, writefds, exceptfds, timeout)";
 
-  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone)
+  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone) : LONGINT
     "gettimeofday(tv, tz)";
 
   PROCEDURE -Read* (fd, buf, nbyte: LONGINT): LONGINT
diff --git a/src/lib/system/gnuc/armv6j_hardfp/Unix.Mod b/src/lib/system/gnuc/armv6j_hardfp/Unix.Mod
index 19d1c019..9e46278e 100644
--- a/src/lib/system/gnuc/armv6j_hardfp/Unix.Mod
+++ b/src/lib/system/gnuc/armv6j_hardfp/Unix.Mod
@@ -254,7 +254,7 @@ TYPE
   PROCEDURE -Select*(width: LONGINT; VAR readfds, writefds, exceptfds: FdSet; VAR timeout: Timeval): LONGINT
     "select(width, readfds, writefds, exceptfds, timeout)";
 
-  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone)
+  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone) : LONGINT
     "gettimeofday(tv, tz)";
 
   PROCEDURE -Read* (fd, buf, nbyte: LONGINT): LONGINT
diff --git a/src/lib/system/gnuc/armv7a_hardfp/Unix.Mod b/src/lib/system/gnuc/armv7a_hardfp/Unix.Mod
index 19d1c019..9e46278e 100644
--- a/src/lib/system/gnuc/armv7a_hardfp/Unix.Mod
+++ b/src/lib/system/gnuc/armv7a_hardfp/Unix.Mod
@@ -254,7 +254,7 @@ TYPE
   PROCEDURE -Select*(width: LONGINT; VAR readfds, writefds, exceptfds: FdSet; VAR timeout: Timeval): LONGINT
     "select(width, readfds, writefds, exceptfds, timeout)";
 
-  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone)
+  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone) : LONGINT
     "gettimeofday(tv, tz)";
 
   PROCEDURE -Read* (fd, buf, nbyte: LONGINT): LONGINT
diff --git a/src/lib/system/gnuc/x86/Unix.Mod b/src/lib/system/gnuc/x86/Unix.Mod
index 19d1c019..9e46278e 100644
--- a/src/lib/system/gnuc/x86/Unix.Mod
+++ b/src/lib/system/gnuc/x86/Unix.Mod
@@ -254,7 +254,7 @@ TYPE
   PROCEDURE -Select*(width: LONGINT; VAR readfds, writefds, exceptfds: FdSet; VAR timeout: Timeval): LONGINT
     "select(width, readfds, writefds, exceptfds, timeout)";
 
-  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone)
+  PROCEDURE -Gettimeofday* (VAR tv: Timeval; VAR tz: Timezone) : LONGINT
     "gettimeofday(tv, tz)";
 
   PROCEDURE -Read* (fd, buf, nbyte: LONGINT): LONGINT