diff --git a/libgloss/m68k/io-lseek.c b/libgloss/m68k/io-lseek.c
index 63ec56451..eaaf55746 100644
--- a/libgloss/m68k/io-lseek.c
+++ b/libgloss/m68k/io-lseek.c
@@ -38,7 +38,7 @@ off_t lseek (int fd, off_t offset, int whence)
 #if HOSTED
   gdb_parambuf_t parameters;
   parameters[0] = (uint32_t) fd;
-  parameters[1] = (uint32_t) ((offset >> 32) & 0xffffffff);
+  parameters[1] = (uint32_t) ((int64_t)offset >> 32);
   parameters[2] = (uint32_t) (offset & 0xffffffff);
   parameters[3] = __hosted_to_gdb_lseek_flags (whence);
   __hosted (HOSTED_LSEEK, parameters);
diff --git a/libgloss/nios2/io-lseek.c b/libgloss/nios2/io-lseek.c
index bfc23c1bc..d47fe0798 100644
--- a/libgloss/nios2/io-lseek.c
+++ b/libgloss/nios2/io-lseek.c
@@ -39,7 +39,7 @@ off_t lseek (int fd, off_t offset, int whence)
 #if HOSTED
   gdb_parambuf_t parameters;
   parameters[0] = (uint32_t) fd;
-  parameters[1] = (uint32_t) ((offset >> 32) & 0xffffffff);
+  parameters[1] = (uint32_t) ((int64_t)offset >> 32);
   parameters[2] = (uint32_t) (offset & 0xffffffff);
   parameters[3] = __hosted_to_gdb_lseek_flags (whence);
   __io_hosted (HOSTED_LSEEK, parameters);