diff --git a/Dockerfile b/Dockerfile
index 9acf6a8f7..f70a0855d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -23,7 +23,7 @@ ARG TARGETARCH
 
 RUN go get ./...
 RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
-    go build -ldflags "-X main.metadataString=container"
+    go build -ldflags "-X github.com/GoogleCloudPlatform/cloud-sql-proxy/v2/cmd.metadataString=container"
 
 # Final Stage
 FROM gcr.io/distroless/static:nonroot
diff --git a/Dockerfile.alpine b/Dockerfile.alpine
index 00e38c03d..164336e58 100644
--- a/Dockerfile.alpine
+++ b/Dockerfile.alpine
@@ -23,7 +23,7 @@ ARG TARGETARCH
 
 RUN go get ./...
 RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
-    go build -ldflags "-X main.metadataString=container.alpine"
+    go build -ldflags "-X github.com/GoogleCloudPlatform/cloud-sql-proxy/v2/cmd.metadataString=container.alpine"
 
 # Final stage
 FROM alpine:3
diff --git a/Dockerfile.bullseye b/Dockerfile.bullseye
index af50feb5a..e12530e59 100644
--- a/Dockerfile.bullseye
+++ b/Dockerfile.bullseye
@@ -23,7 +23,7 @@ ARG TARGETARCH
 
 RUN go get ./...
 RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
-    go build -ldflags "-X main.metadataString=container.bullseye"
+    go build -ldflags "-X github.com/GoogleCloudPlatform/cloud-sql-proxy/v2/cmd.metadataString=container.bullseye"
 
 # Final stage
 FROM debian:bullseye
diff --git a/Dockerfile.buster b/Dockerfile.buster
index 924010962..14b220dfe 100644
--- a/Dockerfile.buster
+++ b/Dockerfile.buster
@@ -23,7 +23,7 @@ ARG TARGETARCH
 
 RUN go get ./...
 RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
-    go build -ldflags "-X main.metadataString=container.buster"
+    go build -ldflags "-X github.com/GoogleCloudPlatform/cloud-sql-proxy/v2/cmd.metadataString=container.buster"
 
 # Final stage
 FROM debian:buster
diff --git a/cmd/root.go b/cmd/root.go
index 0d53517b4..d7d1a87ab 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -47,13 +47,25 @@ import (
 var (
 	// versionString indicates the version of this library.
 	//go:embed version.txt
-	versionString    string
-	defaultUserAgent string
+	versionString string
+	// metadataString indiciates additional build or distribution metadata.
+	metadataString string
+	userAgent      string
 )
 
 func init() {
-	versionString = strings.TrimSpace(versionString)
-	defaultUserAgent = "cloud-sql-proxy/" + versionString
+	versionString = semanticVersion()
+	userAgent = "cloud-sql-proxy/" + versionString
+}
+
+// semanticVersion returns the version of the proxy including an compile-time
+// metadata.
+func semanticVersion() string {
+	v := strings.TrimSpace(versionString)
+	if metadataString != "" {
+		v += "+" + metadataString
+	}
+	return v
 }
 
 // Execute adds all child commands to the root command and sets flags appropriately.
@@ -301,7 +313,7 @@ func NewCommand(opts ...Option) *Command {
 		logger:  logger,
 		cleanup: func() error { return nil },
 		conf: &proxy.Config{
-			UserAgent: defaultUserAgent,
+			UserAgent: userAgent,
 		},
 	}
 	for _, o := range opts {
@@ -495,8 +507,8 @@ func parseConfig(cmd *Command, conf *proxy.Config, args []string) error {
 	}
 
 	if userHasSet("user-agent") {
-		defaultUserAgent += " " + cmd.conf.OtherUserAgents
-		conf.UserAgent = defaultUserAgent
+		userAgent += " " + cmd.conf.OtherUserAgents
+		conf.UserAgent = userAgent
 	}
 
 	if userHasSet("sqladmin-api-endpoint") && conf.APIEndpointURL != "" {
diff --git a/cmd/root_test.go b/cmd/root_test.go
index 64d43821a..b06529af7 100644
--- a/cmd/root_test.go
+++ b/cmd/root_test.go
@@ -34,7 +34,7 @@ import (
 
 func withDefaults(c *proxy.Config) *proxy.Config {
 	if c.UserAgent == "" {
-		c.UserAgent = defaultUserAgent
+		c.UserAgent = userAgent
 	}
 	if c.Addr == "" {
 		c.Addr = "127.0.0.1"