diff --git a/local.c b/local.c
index c5b6383..ad0aa34 100644
--- a/local.c
+++ b/local.c
@@ -349,13 +349,8 @@ LCL_CookTime(struct timeval *raw, struct timeval *cooked, double *err)
 void
 LCL_GetOffsetCorrection(struct timeval *raw, double *correction, double *err)
 {
-  double e;
-
   /* Call system specific driver to get correction */
-  (*drv_offset_convert)(raw, correction, &e);
-
-  if (err)
-    *err = e;
+  (*drv_offset_convert)(raw, correction, err);
 }
 
 /* ================================================== */
diff --git a/sys_linux.c b/sys_linux.c
index 48eeeb8..8567df9 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -800,7 +800,6 @@ get_offset_correction(struct timeval *raw,
       slow_slewing = 0;
     }
   }
-  update_slow_slew_error(offset);
 
   if (!nano_slewing) {
     noffset = 0;
@@ -812,7 +811,6 @@ get_offset_correction(struct timeval *raw,
       nano_slewing = 0;
     }
   }
-  update_nano_slew_error(noffset, 0);
 
   if (fast_slewing) {
     UTI_DiffTimevalsToDouble(&fast_slew_duration, raw, &slew_start_tv);
@@ -824,7 +822,12 @@ get_offset_correction(struct timeval *raw,
   }  
 
   *corr = - (offset_register + fast_slew_remaining) + offset / 1.0e6 + noffset / 1.0e9;
-  *err = get_slow_slew_error(raw) + get_fast_slew_error(raw) + get_nano_slew_error();;
+
+  if (err) {
+    update_slow_slew_error(offset);
+    update_nano_slew_error(noffset, 0);
+    *err = get_slow_slew_error(raw) + get_fast_slew_error(raw) + get_nano_slew_error();;
+  }
 
   return;
 }
diff --git a/sys_netbsd.c b/sys_netbsd.c
index 04b3f92..8c0cacc 100644
--- a/sys_netbsd.c
+++ b/sys_netbsd.c
@@ -271,7 +271,8 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
-  *err = 0.0;
+  if (err)
+    *err = 0.0;
 }
 
 /* ================================================== */
diff --git a/sys_solaris.c b/sys_solaris.c
index 4024048..f75485a 100644
--- a/sys_solaris.c
+++ b/sys_solaris.c
@@ -300,7 +300,8 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
-  *err = 0.0;
+  if (err)
+    *err = 0.0;
   return;
 }
 
diff --git a/sys_sunos.c b/sys_sunos.c
index 4878715..6540fa6 100644
--- a/sys_sunos.c
+++ b/sys_sunos.c
@@ -287,7 +287,8 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
-  *err = 0.0;
+  if (err)
+    *err = 0.0;
   return;
 }