diff --git a/src/sewerrat/deregister.py b/src/sewerrat/deregister.py
index 267b2af..bc881d5 100644
--- a/src/sewerrat/deregister.py
+++ b/src/sewerrat/deregister.py
@@ -5,7 +5,7 @@
 from . import _utils as ut
 
 
-def deregister(path: str, url: str, wait: float = 1):
+def deregister(path: str, url: str, retry: int = 3, wait: float = 1):
     """
     Deregister a directory from the SewerRat search index. It is assumed that
     this directory is world-readable and that the caller has write access to
@@ -18,9 +18,14 @@ def deregister(path: str, url: str, wait: float = 1):
         url:
             URL to the SewerRat REST API. 
 
+        retry:
+            Number of times to try to finish the registration. Larger values
+            may be necessary if ``path`` is in a network share that takes some
+            time to synchronise.
+
         wait:
             Number of seconds to wait for a file write to synchronise before
-            requesting verification.
+            requesting verification during each retry.
     """
     path = os.path.abspath(path)
     res = requests.post(url + "/deregister/start", json = { "path": path }, allow_redirects=True)
@@ -37,13 +42,19 @@ def deregister(path: str, url: str, wait: float = 1):
     with open(target, "w") as handle:
         pass
 
-    # Sleeping for a while so that files can sync on network shares.
-    time.sleep(wait)
-
     try:
-        res = requests.post(url + "/deregister/finish", json = { "path": path }, allow_redirects=True)
-        if res.status_code >= 300:
-            raise ut.format_error(res)
+        for t in range(retry):
+            # Sleeping for a while so that files can sync on network shares.
+            time.sleep(wait)
+
+            res = requests.post(url + "/deregister/finish", json = { "path": path }, allow_redirects=True)
+            if res.status_code < 300:
+                break
+
+            # Only looping if the status code is an Unauth failure and we're not on the last loop iteration.
+            if res.status_code != 401 or t + 1 == retry:
+                raise ut.format_error(res)
+
     finally:
         os.unlink(target)
 
diff --git a/src/sewerrat/register.py b/src/sewerrat/register.py
index 4f8daae..36fe312 100644
--- a/src/sewerrat/register.py
+++ b/src/sewerrat/register.py
@@ -7,7 +7,7 @@
 from . import _utils as ut
 
 
-def register(path: str, names: List[str], url: str, wait: int = 1):
+def register(path: str, names: List[str], url: str, retry: int = 3, wait: int = 1):
     """
     Register a directory into the SewerRat search index. It is assumed that
     that the directory is world-readable and that the caller has write access.
@@ -26,9 +26,14 @@ def register(path: str, names: List[str], url: str, wait: int = 1):
         url:
             URL to the SewerRat REST API.
 
+        retry:
+            Number of times to try to finish the registration. Larger values
+            may be necessary if ``path`` is in a network share that takes some
+            time to synchronise.
+
         wait:
             Number of seconds to wait for a file write to synchronise before
-            requesting verification.
+            requesting verification during each retry.
     """
     if len(names) == 0:
         raise ValueError("expected at least one entry in 'names'")
@@ -47,14 +52,20 @@ def register(path: str, names: List[str], url: str, wait: int = 1):
     with open(target, "w") as handle:
         handle.write("")
 
-    # Sleeping for a while so that files can sync on network shares.
-    time.sleep(wait)
-
     try:
-        res = requests.post(url + "/register/finish", json = { "path": path, "base": names }, allow_redirects=True)
-        if res.status_code >= 300:
-            raise ut.format_error(res)
-        body = res.json()
+        for t in range(retry):
+            # Sleeping for a while so that files can sync on network shares.
+            time.sleep(wait)
+
+            res = requests.post(url + "/register/finish", json = { "path": path, "base": names }, allow_redirects=True)
+            if res.status_code < 300:
+                body = res.json()
+                break
+
+            # Only looping if the status code is an Unauth failure and we're not on the last loop iteration.
+            if res.status_code != 401 or t + 1 == retry:
+                raise ut.format_error(res)
+
     finally:
         os.unlink(target)