diff --git a/grpc/interceptors.go b/grpc/interceptors.go
index fdedc72bbb4..adb609c1e37 100644
--- a/grpc/interceptors.go
+++ b/grpc/interceptors.go
@@ -25,11 +25,9 @@ const (
 	returnOverhead         = 20 * time.Millisecond
 	meaningfulWorkOverhead = 100 * time.Millisecond
 	clientRequestTimeKey   = "client-request-time"
-	userAgentKey           = "acme-client-user-agent"
 	// We use the "-bin" suffix to tell grpc's metadata package not to require the user-agent
 	// be printable ASCII. It's rare, but ACME clients can send non-ASCII user-agents.
-	// Remove `userAgentKey` once this has been deployed.
-	userAgentKey2 = "acme-client-user-agent-bin"
+	userAgentKey = "acme-client-user-agent-bin"
 )
 
 type serverInterceptor interface {
@@ -95,9 +93,7 @@ func (smi *serverMetadataInterceptor) Unary(
 				return nil, err
 			}
 		}
-		if len(md[userAgentKey2]) > 0 {
-			ctx = web.WithUserAgent(ctx, md[userAgentKey2][0])
-		} else if len(md[userAgentKey]) > 0 {
+		if len(md[userAgentKey]) > 0 {
 			ctx = web.WithUserAgent(ctx, md[userAgentKey][0])
 		}
 	}
@@ -281,8 +277,6 @@ func (cmi *clientMetadataInterceptor) Unary(
 	// Create a grpc/metadata.Metadata instance for the request metadata.
 	reqMD := metadata.New(map[string]string{
 		clientRequestTimeKey: nowTS,
-		userAgentKey:         web.UserAgent(ctx),
-		userAgentKey2:        web.UserAgent(ctx),
 	})
 	// Configure the localCtx with the metadata so it gets sent along in the request
 	localCtx = metadata.NewOutgoingContext(localCtx, reqMD)
@@ -390,8 +384,6 @@ func (cmi *clientMetadataInterceptor) Stream(
 	// Initialize it with the request time.
 	reqMD := metadata.New(map[string]string{
 		clientRequestTimeKey: nowTS,
-		userAgentKey:         web.UserAgent(ctx),
-		userAgentKey2:        web.UserAgent(ctx),
 	})
 	// Configure the localCtx with the metadata so it gets sent along in the request
 	localCtx = metadata.NewOutgoingContext(localCtx, reqMD)