diff --git a/tests/axis-type/test-ui.py b/tests/axis-type/test-ui.py
index 84efee09928..41984fcaff3 100755
--- a/tests/axis-type/test-ui.py
+++ b/tests/axis-type/test-ui.py
@@ -30,10 +30,14 @@ def wait_ready(timeout=20.0):
     fail("linuxcnc did not come up")
 
 
+# a realtime host may report a late servo period; not this test's error
 def errors():
-    err = e.poll()
-    if err:
-        fail("error: %s" % err[1])
+    while True:
+        err = e.poll()
+        if not err:
+            return
+        if "Unexpected realtime delay" not in err[1]:
+            fail("error: %s" % err[1])
 
 
 def mdi(cmd, timeout=20.0):
diff --git a/tests/jog-speed-change/test-ui.py b/tests/jog-speed-change/test-ui.py
index 7df224f15c3..a27fef12831 100755
--- a/tests/jog-speed-change/test-ui.py
+++ b/tests/jog-speed-change/test-ui.py
@@ -31,6 +31,9 @@ def drain():
         if not m:
             break
         print("channel:", m)
+        # a realtime host may report a late servo period; not this test's error
+        if "Unexpected realtime delay" in m[1]:
+            continue
         if m[0] in (linuxcnc.NML_ERROR, linuxcnc.OPERATOR_ERROR):
             error("reported: %s" % m[1].strip())
 
diff --git a/tests/kins-switch/test-ui.py b/tests/kins-switch/test-ui.py
index e62800c5cd7..c74fe8f8b3c 100755
--- a/tests/kins-switch/test-ui.py
+++ b/tests/kins-switch/test-ui.py
@@ -29,10 +29,17 @@ def joints():
 def kins_type():
     return int(round(hal.get_value("motion.kins-type")))
 
+# a realtime host may report a late servo period; not this test's error
+def poll():
+    while True:
+        m = e.poll()
+        if not m or "Unexpected realtime delay" not in m[1]:
+            return m
+
 def drain():
     said = []
     while True:
-        m = e.poll()
+        m = poll()
         if not m:
             return said
         said.append(m)
@@ -201,7 +208,7 @@ def mdi(cmd):
 drain()
 c.mdi("G12.1 P-1")
 c.wait_complete(30)
-m = e.poll()
+m = poll()
 if not m or m[0] not in (linuxcnc.NML_ERROR, linuxcnc.OPERATOR_ERROR):
     error("G12.1 P-1 was accepted")
 elif "non-negative" not in m[1]:
@@ -214,7 +221,7 @@ def mdi(cmd):
 
 c.mdi("G12.1 P7")
 c.wait_complete(30)
-m = e.poll()
+m = poll()
 if not m or m[0] not in (linuxcnc.NML_ERROR, linuxcnc.OPERATOR_ERROR):
     error("G12.1 P7 was accepted")
 elif "does not name" not in m[1]:
diff --git a/tests/kins-switchkins-core/test-ui.py b/tests/kins-switchkins-core/test-ui.py
index 2e6595199f1..9cd0e513f0e 100755
--- a/tests/kins-switchkins-core/test-ui.py
+++ b/tests/kins-switchkins-core/test-ui.py
@@ -28,13 +28,15 @@ def joints():
     s.poll()
     return tuple(round(v, 6) for v in s.joint_position[:3])
 
+# a realtime host may report a late servo period; not this test's error
 def drain():
     said = []
     while True:
         m = e.poll()
         if not m:
             return said
-        said.append(m[1])
+        if "Unexpected realtime delay" not in m[1]:
+            said.append(m[1])
 
 def wait_idle():
     deadline = time.time() + 30
diff --git a/tests/linuxcncrsh/checkresult b/tests/linuxcncrsh/checkresult
index 86cfdbed080..e6798dc2acd 100755
--- a/tests/linuxcncrsh/checkresult
+++ b/tests/linuxcncrsh/checkresult
@@ -5,7 +5,10 @@ cd "$TEST_DIR" || { echo "E: Could not change directory to '$TEST_DIR'"; exit 1;
 
 # show deviation from expected output
 diff -uwB expected-gcode-output gcode-output || exit 1
-diff -uwB expected-telnet-output telnet-output || exit 1
+# a realtime host may report a late servo period, which one 'get error'
+# then returns in place of OK
+diff -uwB expected-telnet-output \
+    <(sed '/^ERROR Unexpected realtime delay/{N;N;s/.*/ERROR OK/}' telnet-output) || exit 1
 
 # search all output for possible errors
 grep 'error_type' result && exit 1
diff --git a/tests/m62-m68-range/test-ui.py b/tests/m62-m68-range/test-ui.py
index 4e58bef2ff4..0da0d9ddcd7 100755
--- a/tests/m62-m68-range/test-ui.py
+++ b/tests/m62-m68-range/test-ui.py
@@ -24,6 +24,9 @@ def errors():
         error = e.poll()
         if not error:
             return out
+        # a realtime host may report a late servo period; not this test's error
+        if "Unexpected realtime delay" in error[1]:
+            continue
         print("  linuxcnc error: %s" % error[1].strip())
         out.append(error[1])
 
diff --git a/tests/probe-queue-not-empty/test-ui.py b/tests/probe-queue-not-empty/test-ui.py
index 10a9c9632ef..10ab2222392 100755
--- a/tests/probe-queue-not-empty/test-ui.py
+++ b/tests/probe-queue-not-empty/test-ui.py
@@ -54,11 +54,16 @@ def wait_for(what, done):
         sys.exit(1)
     time.sleep(0.001)
 
+# servo_delay busy waits inside the servo period, so a realtime host may
+# report a late period; only the other errors count.
+def error(err):
+    if err and "Unexpected realtime delay" not in err[1]:
+        errors.append(err[1])
+
 errors = []
 while True:
     err = e.poll()
-    if err:
-        errors.append(err[1])
+    error(err)
     s.poll()
     if s.interp_state == linuxcnc.INTERP_IDLE:
         break
@@ -69,7 +74,7 @@ def wait_for(what, done):
 
 err = e.poll()
 while err:
-    errors.append(err[1])
+    error(err)
     err = e.poll()
 
 for msg in errors:
diff --git a/tests/tlo/test-ui.py b/tests/tlo/test-ui.py
index 42fe9390895..2d87b4e2037 100755
--- a/tests/tlo/test-ui.py
+++ b/tests/tlo/test-ui.py
@@ -213,7 +213,10 @@ def verify_tool(tool, x, y, z, a, b, c, u, v, w, diameter, front_angle, back_ang
 
 c.mdi('g43.2')
 c.wait_complete()
+# a realtime host may report a late servo period first; skip it
 error = e.poll()
+while error and "Unexpected realtime delay" in error[1]:
+    error = e.poll()
 if error[1] != "G43.2: No axes specified and H word missing":
     print("G43.2 with missing H-word did not produce expected error")
     print("got [%s]" % error[1])
diff --git a/tests/tp/helix-motion/test-ui.py b/tests/tp/helix-motion/test-ui.py
index e62b22f3d26..b359b685ab3 100755
--- a/tests/tp/helix-motion/test-ui.py
+++ b/tests/tp/helix-motion/test-ui.py
@@ -27,6 +27,9 @@ def check_errors():
         error = errors.poll()
         if error is None:
             return
+        # a realtime host may report a late servo period; not this test's error
+        if "Unexpected realtime delay" in error[1]:
+            continue
         if error[0] in (linuxcnc.NML_ERROR, linuxcnc.OPERATOR_ERROR):
             raise RuntimeError(error[1])
 
diff --git a/tests/workplane-preview/test-ui.py b/tests/workplane-preview/test-ui.py
index e52f1759059..3b669de0e03 100755
--- a/tests/workplane-preview/test-ui.py
+++ b/tests/workplane-preview/test-ui.py
@@ -54,13 +54,15 @@ def say(*a):
 c.home(-1)
 l.wait_for_home(joints=[1, 1, 1, 1, 0, 0, 0, 0, 0])
 
+# a realtime host may report a late servo period; not this test's error
 def errors():
     msgs = []
     while True:
         m = e.poll()
         if not m:
             return msgs
-        msgs.append(m[1])
+        if "Unexpected realtime delay" not in m[1]:
+            msgs.append(m[1])
 
 def mdi(*cmds):
     c.mode(linuxcnc.MODE_MDI)