diff --git a/lib/services/db.js b/lib/services/db.js
index 042c7bab..732e4fc5 100644
--- a/lib/services/db.js
+++ b/lib/services/db.js
@@ -366,15 +366,22 @@ DB.prototype.runAllBlockHandlers = function(block, add, callback) {
   async.eachSeries(
     this.node.services,
     function(mod, next) {
-      mod.blockHandler.call(mod, block, add, function(err, ops) {
-        if (err) {
-          return next(err);
-        }
-        if (ops) {
-          operations = operations.concat(ops);
-        }
-        next();
-      });
+      if(mod.blockHandler) {
+        $.checkArgument(typeof mod.blockHandler === 'function', 'blockHandler must be a function');
+
+        mod.blockHandler.call(mod, block, add, function(err, ops) {
+          if (err) {
+            return next(err);
+          }
+          if (ops) {
+            $.checkArgument(Array.isArray(ops), 'blockHandler for ' + mod.name + ' returned non-array');
+            operations = operations.concat(ops);
+          }
+          next();
+        });
+      } else {
+        setImmediate(next);
+      }
     },
     function(err) {
       if (err) {
diff --git a/test/services/db.unit.js b/test/services/db.unit.js
index a2293df4..867f49cb 100644
--- a/test/services/db.unit.js
+++ b/test/services/db.unit.js
@@ -630,6 +630,9 @@ describe('DB Service', function() {
     Service1.prototype.blockHandler = sinon.stub().callsArgWith(2, null, ['op1', 'op2', 'op3']);
     var Service2 = function() {};
     Service2.prototype.blockHandler = sinon.stub().callsArgWith(2, null, ['op4', 'op5']);
+    var Service3 = function() {};
+    var Service4 = function() {};
+    Service4.prototype.blockHandler = sinon.stub().callsArgWith(2, null, 'bad-value');
     db.node = {};
     db.node.services = {
       service1: new Service1(),
@@ -657,6 +660,31 @@ describe('DB Service', function() {
         done();
       });
     });
+
+    it('should not give an error if a service does not have blockHandler', function(done) {
+      db.node = {};
+      db.node.services = {
+        service3: new Service3()
+      };
+
+      db.runAllBlockHandlers('block', true, function(err) {
+        should.not.exist(err);
+        done();
+      });
+    });
+
+    it('should throw an error if blockHandler gives unexpected result', function() {
+      db.node = {};
+      db.node.services = {
+        service4: new Service4()
+      };
+
+      (function() {
+        db.runAllBlockHandlers('block', true, function(err) {
+          should.not.exist(err);
+        });
+      }).should.throw('bitcore.ErrorInvalidArgument');
+    });
   });
 
   describe('#getAPIMethods', function() {