diff --git a/go/vt/vtgate/engine/concatenate.go b/go/vt/vtgate/engine/concatenate.go
index e415e683d4f..1e8eb5b3f1a 100644
--- a/go/vt/vtgate/engine/concatenate.go
+++ b/go/vt/vtgate/engine/concatenate.go
@@ -19,8 +19,6 @@ package engine
 import (
 	"sync"
 
-	"vitess.io/vitess/go/sync2"
-
 	"vitess.io/vitess/go/sqltypes"
 	querypb "vitess.io/vitess/go/vt/proto/query"
 	vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
@@ -30,12 +28,12 @@ import (
 // Concatenate Primitive is used to concatenate results from multiple sources.
 var _ Primitive = (*Concatenate)(nil)
 
-//Concatenate specified the parameter for concatenate primitive
+// Concatenate specified the parameter for concatenate primitive
 type Concatenate struct {
 	Sources []Primitive
 }
 
-//RouteType returns a description of the query routing type used by the primitive
+// RouteType returns a description of the query routing type used by the primitive
 func (c *Concatenate) RouteType() string {
 	return "Concatenate"
 }
@@ -146,13 +144,13 @@ func (c *Concatenate) execSources(vcursor VCursor, bindVars map[string]*querypb.
 // TryStreamExecute performs a streaming exec.
 func (c *Concatenate) TryStreamExecute(vcursor VCursor, bindVars map[string]*querypb.BindVariable, wantfields bool, callback func(*sqltypes.Result) error) error {
 	var seenFields []*querypb.Field
-	var fieldset sync.WaitGroup
-	var cbMu sync.Mutex
+	var wg sync.WaitGroup
+	var cbMu, fieldsMu sync.Mutex
 
 	g, restoreCtx := vcursor.ErrorGroupCancellableContext()
 	defer restoreCtx()
-	var fieldsSent sync2.AtomicBool
-	fieldset.Add(1)
+	var fieldsSent bool
+	wg.Add(1)
 
 	for i, source := range c.Sources {
 		currIndex, currSource := i, source
@@ -160,14 +158,19 @@ func (c *Concatenate) TryStreamExecute(vcursor VCursor, bindVars map[string]*que
 		g.Go(func() error {
 			err := vcursor.StreamExecutePrimitive(currSource, bindVars, wantfields, func(resultChunk *sqltypes.Result) error {
 				// if we have fields to compare, make sure all the fields are all the same
-				if currIndex == 0 && !fieldsSent.Get() {
-					defer fieldset.Done()
-					seenFields = resultChunk.Fields
-					fieldsSent.Set(true)
-					// No other call can happen before this call.
-					return callback(resultChunk)
+				if currIndex == 0 {
+					fieldsMu.Lock()
+					if !fieldsSent {
+						defer wg.Done()
+						defer fieldsMu.Unlock()
+						seenFields = resultChunk.Fields
+						fieldsSent = true
+						// No other call can happen before this call.
+						return callback(resultChunk)
+					}
+					fieldsMu.Unlock()
 				}
-				fieldset.Wait()
+				wg.Wait()
 				if resultChunk.Fields != nil {
 					err := compareFields(seenFields, resultChunk.Fields)
 					if err != nil {
@@ -185,9 +188,15 @@ func (c *Concatenate) TryStreamExecute(vcursor VCursor, bindVars map[string]*que
 				}
 			})
 			// This is to ensure other streams complete if the first stream failed to unlock the wait.
-			if currIndex == 0 && !fieldsSent.Get() {
-				fieldset.Done()
+			if currIndex == 0 {
+				fieldsMu.Lock()
+				if !fieldsSent {
+					fieldsSent = true
+					wg.Done()
+				}
+				fieldsMu.Unlock()
 			}
+
 			return err
 		})
 
@@ -218,7 +227,7 @@ func (c *Concatenate) GetFields(vcursor VCursor, bindVars map[string]*querypb.Bi
 	return res, nil
 }
 
-//NeedsTransaction returns whether a transaction is needed for this primitive
+// NeedsTransaction returns whether a transaction is needed for this primitive
 func (c *Concatenate) NeedsTransaction() bool {
 	for _, source := range c.Sources {
 		if source.NeedsTransaction() {
diff --git a/go/vt/vtgate/engine/limit.go b/go/vt/vtgate/engine/limit.go
index 58d6b24b670..de048f6a827 100644
--- a/go/vt/vtgate/engine/limit.go
+++ b/go/vt/vtgate/engine/limit.go
@@ -88,6 +88,8 @@ func (l *Limit) TryStreamExecute(vcursor VCursor, bindVars map[string]*querypb.B
 		return err
 	}
 
+	bindVars = copyBindVars(bindVars)
+
 	// When offset is present, we hijack the limit value so we can calculate
 	// the offset in memory from the result of the scatter query with count + offset.
 	bindVars["__upper_limit"] = sqltypes.Int64BindVariable(int64(count + offset))