diff --git a/CHANGES.txt b/CHANGES.txt
index ac84102522..b7880b259a 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -9,6 +9,7 @@ Merged from 4.1:
 Merged from 4.0:
 Merged from 3.11:
 Merged from 3.0:
+ * Refactor validation logic in StorageService.rebuild (CASSANDRA-18803)
  * Make alternation of a user type validate the same way as creation of a user type does (CASSANDRA-18585)
 
 5.0-alpha1
diff --git a/src/java/org/apache/cassandra/service/StorageService.java b/src/java/org/apache/cassandra/service/StorageService.java
index a33270a77e..c119f2d82b 100644
--- a/src/java/org/apache/cassandra/service/StorageService.java
+++ b/src/java/org/apache/cassandra/service/StorageService.java
@@ -1419,45 +1419,36 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
 
     public void rebuild(String sourceDc, String keyspace, String tokens, String specificSources, boolean excludeLocalDatacenterNodes)
     {
-        try
+        // fail if source DC is local and --exclude-local-dc is set
+        if (sourceDc != null && sourceDc.equals(DatabaseDescriptor.getLocalDataCenter()) && excludeLocalDatacenterNodes)
         {
-            // check ongoing rebuild
-            if (!isRebuilding.compareAndSet(false, true))
-            {
-                throw new IllegalStateException("Node is still rebuilding. Check nodetool netstats.");
-            }
+            throw new IllegalArgumentException("Cannot set source data center to be local data center, when excludeLocalDataCenter flag is set");
+        }
 
-            // fail if source DC is local and --exclude-local-dc is set
-            if (sourceDc != null && sourceDc.equals(DatabaseDescriptor.getLocalDataCenter()) && excludeLocalDatacenterNodes)
+        if (sourceDc != null)
+        {
+            TokenMetadata.Topology topology = getTokenMetadata().cloneOnlyTokenMap().getTopology();
+            Set<String> availableDCs = topology.getDatacenterEndpoints().keySet();
+            if (!availableDCs.contains(sourceDc))
             {
-                throw new IllegalArgumentException("Cannot set source data center to be local data center, when excludeLocalDataCenter flag is set");
-            }
-
-            if (sourceDc != null)
-            {
-                TokenMetadata.Topology topology = getTokenMetadata().cloneOnlyTokenMap().getTopology();
-                Set<String> availableDCs = topology.getDatacenterEndpoints().keySet();
-                if (!availableDCs.contains(sourceDc))
-                {
-                    throw new IllegalArgumentException(String.format("Provided datacenter '%s' is not a valid datacenter, available datacenters are: %s",
-                                                                     sourceDc, String.join(",", availableDCs)));
-                }
+                throw new IllegalArgumentException(String.format("Provided datacenter '%s' is not a valid datacenter, available datacenters are: %s",
+                                                                 sourceDc, String.join(",", availableDCs)));
             }
         }
-        catch (Throwable ex)
+
+        if (keyspace == null && tokens != null)
         {
-            isRebuilding.set(false);
-            throw ex;
+            throw new IllegalArgumentException("Cannot specify tokens without keyspace.");
+        }
+
+        // check ongoing rebuild
+        if (!isRebuilding.compareAndSet(false, true))
+        {
+            throw new IllegalStateException("Node is still rebuilding. Check nodetool netstats.");
         }
 
         try
         {
-            // check the arguments
-            if (keyspace == null && tokens != null)
-            {
-                throw new IllegalArgumentException("Cannot specify tokens without keyspace.");
-            }
-
             logger.info("rebuild from dc: {}, {}, {}", sourceDc == null ? "(any dc)" : sourceDc,
                         keyspace == null ? "(All keyspaces)" : keyspace,
                         tokens == null ? "(All tokens)" : tokens);