diff --git a/go.mod b/go.mod
index 77b39b82b..d54d86d32 100644
--- a/go.mod
+++ b/go.mod
@@ -12,3 +12,5 @@ require (
 	go.elastic.co/fastjson v1.0.0
 	golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e
 )
+
+go 1.13
diff --git a/internal/tracecontexttest/go.mod b/internal/tracecontexttest/go.mod
index 12d179697..fa1032113 100644
--- a/internal/tracecontexttest/go.mod
+++ b/internal/tracecontexttest/go.mod
@@ -5,3 +5,5 @@ require go.elastic.co/apm/module/apmhttp v1.5.0
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../../module/apmhttp
+
+go 1.13
diff --git a/module/apmbeego/go.mod b/module/apmbeego/go.mod
index 75c47a704..06807dc04 100644
--- a/module/apmbeego/go.mod
+++ b/module/apmbeego/go.mod
@@ -14,3 +14,5 @@ replace go.elastic.co/apm => ../..
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
 
 replace go.elastic.co/apm/module/apmsql => ../apmsql
+
+go 1.13
diff --git a/module/apmchi/go.mod b/module/apmchi/go.mod
index b2ba92883..c5c8239d5 100644
--- a/module/apmchi/go.mod
+++ b/module/apmchi/go.mod
@@ -10,3 +10,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmecho/go.mod b/module/apmecho/go.mod
index 073e25700..dd9145710 100644
--- a/module/apmecho/go.mod
+++ b/module/apmecho/go.mod
@@ -17,3 +17,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmechov4/go.mod b/module/apmechov4/go.mod
index 6edbc57bb..3ddf78ef6 100644
--- a/module/apmechov4/go.mod
+++ b/module/apmechov4/go.mod
@@ -12,3 +12,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmelasticsearch/go.mod b/module/apmelasticsearch/go.mod
index 6589db470..366fb7851 100644
--- a/module/apmelasticsearch/go.mod
+++ b/module/apmelasticsearch/go.mod
@@ -10,3 +10,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmelasticsearch/internal/integration/go.mod b/module/apmelasticsearch/internal/integration/go.mod
index db29c870c..529bfdae0 100644
--- a/module/apmelasticsearch/internal/integration/go.mod
+++ b/module/apmelasticsearch/internal/integration/go.mod
@@ -14,3 +14,5 @@ replace go.elastic.co/apm => ../../../..
 replace go.elastic.co/apm/module/apmelasticsearch => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../../../apmhttp
+
+go 1.13
diff --git a/module/apmgin/go.mod b/module/apmgin/go.mod
index 7ef0dff60..1fb1e6148 100644
--- a/module/apmgin/go.mod
+++ b/module/apmgin/go.mod
@@ -11,3 +11,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmgocql/go.mod b/module/apmgocql/go.mod
index ffb574f75..75fff3757 100644
--- a/module/apmgocql/go.mod
+++ b/module/apmgocql/go.mod
@@ -9,3 +9,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmgokit/go.mod b/module/apmgokit/go.mod
index 1ca20e726..9858a5d31 100644
--- a/module/apmgokit/go.mod
+++ b/module/apmgokit/go.mod
@@ -18,3 +18,5 @@ replace go.elastic.co/apm => ../..
 replace go.elastic.co/apm/module/apmgrpc => ../apmgrpc
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmgometrics/go.mod b/module/apmgometrics/go.mod
index 2bcdbf6e1..17f581b5c 100644
--- a/module/apmgometrics/go.mod
+++ b/module/apmgometrics/go.mod
@@ -7,3 +7,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmgopg/go.mod b/module/apmgopg/go.mod
index aeb64a46b..8a2384b6f 100644
--- a/module/apmgopg/go.mod
+++ b/module/apmgopg/go.mod
@@ -18,3 +18,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmsql => ../apmsql
+
+go 1.13
diff --git a/module/apmgorilla/go.mod b/module/apmgorilla/go.mod
index 759ffefd3..661bad967 100644
--- a/module/apmgorilla/go.mod
+++ b/module/apmgorilla/go.mod
@@ -11,3 +11,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmgorm/go.mod b/module/apmgorm/go.mod
index 6944dd669..d7073a3ff 100644
--- a/module/apmgorm/go.mod
+++ b/module/apmgorm/go.mod
@@ -14,3 +14,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmsql => ../apmsql
+
+go 1.13
diff --git a/module/apmgrpc/go.mod b/module/apmgrpc/go.mod
index 197577750..9e96ceeb8 100644
--- a/module/apmgrpc/go.mod
+++ b/module/apmgrpc/go.mod
@@ -12,3 +12,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmhttp/go.mod b/module/apmhttp/go.mod
index 185021204..0ad3f313f 100644
--- a/module/apmhttp/go.mod
+++ b/module/apmhttp/go.mod
@@ -9,3 +9,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmhttprouter/go.mod b/module/apmhttprouter/go.mod
index 6e4b38bb5..76ce234c7 100644
--- a/module/apmhttprouter/go.mod
+++ b/module/apmhttprouter/go.mod
@@ -10,3 +10,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmlambda/go.mod b/module/apmlambda/go.mod
index d703769c4..c1019114c 100644
--- a/module/apmlambda/go.mod
+++ b/module/apmlambda/go.mod
@@ -6,3 +6,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmlogrus/go.mod b/module/apmlogrus/go.mod
index 078a2bbb0..e22837884 100644
--- a/module/apmlogrus/go.mod
+++ b/module/apmlogrus/go.mod
@@ -9,3 +9,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmmongo/go.mod b/module/apmmongo/go.mod
index ab0e187bf..f925e7f86 100644
--- a/module/apmmongo/go.mod
+++ b/module/apmmongo/go.mod
@@ -15,3 +15,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmot/go.mod b/module/apmot/go.mod
index 6fa9aa38d..96d103b66 100644
--- a/module/apmot/go.mod
+++ b/module/apmot/go.mod
@@ -10,3 +10,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmprometheus/go.mod b/module/apmprometheus/go.mod
index fbc175e65..66ed54530 100644
--- a/module/apmprometheus/go.mod
+++ b/module/apmprometheus/go.mod
@@ -9,3 +9,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmredigo/go.mod b/module/apmredigo/go.mod
index 3234317de..e07a9c31f 100644
--- a/module/apmredigo/go.mod
+++ b/module/apmredigo/go.mod
@@ -7,3 +7,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmrestful/go.mod b/module/apmrestful/go.mod
index a1c467fa4..712563883 100644
--- a/module/apmrestful/go.mod
+++ b/module/apmrestful/go.mod
@@ -13,3 +13,5 @@ require (
 replace go.elastic.co/apm => ../..
 
 replace go.elastic.co/apm/module/apmhttp => ../apmhttp
+
+go 1.13
diff --git a/module/apmsql/go.mod b/module/apmsql/go.mod
index 7dd21a9cb..fde932c6e 100644
--- a/module/apmsql/go.mod
+++ b/module/apmsql/go.mod
@@ -10,3 +10,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmzap/go.mod b/module/apmzap/go.mod
index 0cc1f9a16..9ed1a1cb0 100644
--- a/module/apmzap/go.mod
+++ b/module/apmzap/go.mod
@@ -10,3 +10,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/module/apmzerolog/go.mod b/module/apmzerolog/go.mod
index 6c47d138b..f177ccc64 100644
--- a/module/apmzerolog/go.mod
+++ b/module/apmzerolog/go.mod
@@ -8,3 +8,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/scripts/genmod/go.mod b/scripts/genmod/go.mod
index adb8c403b..f38ba298c 100644
--- a/scripts/genmod/go.mod
+++ b/scripts/genmod/go.mod
@@ -6,3 +6,5 @@ require (
 )
 
 replace go.elastic.co/apm => ../..
+
+go 1.13
diff --git a/scripts/genmod/main.go b/scripts/genmod/main.go
index 0fc102d01..6ec4212d6 100644
--- a/scripts/genmod/main.go
+++ b/scripts/genmod/main.go
@@ -22,6 +22,7 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"go/build"
 	"io/ioutil"
 	"log"
 	"os"
@@ -130,7 +131,7 @@ func updateModule(dir string, gomod *GoMod, modules map[string]*GoMod) error {
 			"-replace", require.Path+"="+relDir,
 		)
 		cmd.Env = append(os.Environ(), "GO111MODULE=on")
-		cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid")
+		cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid", "GOSUMDB=sum.golang.org https://sum.golang.org")
 		cmd.Stderr = os.Stderr
 		cmd.Dir = dir
 		if err := cmd.Run(); err != nil {
@@ -198,18 +199,18 @@ func checkModuleComplete(dir string, gomod *GoMod, modules map[string]*GoMod) er
 	cmd.Stderr = os.Stderr
 	cmd.Dir = gomod.dir
 	if err := cmd.Run(); err != nil {
-		return err
+		return errors.Wrap(err, "'go mod download' failed")
 	}
 
 	// Check we can build the module's tests and its transitive dependencies
 	// without updating go.mod.
 	cmd = exec.Command("go", "test", "-c", "-mod=readonly", "-o", os.DevNull)
 	cmd.Env = append(os.Environ(), "GO111MODULE=on")
-	cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid")
+	cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid", "GOSUMDB=sum.golang.org https://sum.golang.org")
 	cmd.Stderr = os.Stderr
 	cmd.Dir = gomod.dir
 	if err := cmd.Run(); err != nil {
-		return err
+		return errors.Wrap(err, "'go test' failed")
 	}
 
 	// We create a temporary program which imports the module, and then
@@ -243,6 +244,9 @@ func main() {}
 		gomod := modules[path]
 		fmt.Fprintf(&tmpGomodContent, "\nreplace %s => %s\n", path, gomod.dir)
 	}
+	// Add "go <version>", using the latest release tag.
+	tags := build.Default.ReleaseTags
+	fmt.Fprintf(&tmpGomodContent, "\ngo %s\n", tags[len(tags)-1][2:])
 
 	if err := ioutil.WriteFile(tmpGomodPath, tmpGomodContent.Bytes(), 0644); err != nil {
 		return err
@@ -253,7 +257,7 @@ func main() {}
 
 	cmd = exec.Command("go", "mod", "tidy", "-v")
 	cmd.Env = append(os.Environ(), "GO111MODULE=on")
-	cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid")
+	cmd.Env = append(cmd.Env, "GOPROXY=http://proxy.invalid", "GOSUMDB=sum.golang.org https://sum.golang.org")
 	cmd.Stderr = os.Stderr
 	cmd.Dir = tmpdir
 	if err := cmd.Run(); err != nil {