diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1a686581..f1833fbd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -10,7 +10,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.14.x, 1.15.x]
+        go-version: [1.15.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
@@ -27,6 +27,7 @@ jobs:
 
   test-gotip:
     runs-on: ubuntu-latest
+    continue-on-error: true # master breaks sometimes
     steps:
     - name: Install Go
       run: |
diff --git a/README.md b/README.md
index b7d997bd..09118e5f 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,8 @@
 
 	GO111MODULE=on go get mvdan.cc/garble
 
-Obfuscate a Go build. Requires Go 1.14 or later.
+Obfuscate a Go build. Requires Go 1.15 or later, since Go 1.14 uses an entirely
+different object format.
 
 	garble build [build flags] [packages]
 
diff --git a/go.mod b/go.mod
index f253c1b1..38622213 100644
--- a/go.mod
+++ b/go.mod
@@ -1,9 +1,10 @@
 module mvdan.cc/garble
 
-go 1.14
+go 1.15
 
 require (
-	github.com/google/go-cmp v0.5.1
-	github.com/rogpeppe/go-internal v1.6.0
-	golang.org/x/tools v0.0.0-20200622203043-20e05c1c8ffa
+	github.com/google/go-cmp v0.5.2
+	github.com/rogpeppe/go-internal v1.6.1
+	golang.org/x/mod v0.3.1-0.20200828183125-ce943fd02449
+	golang.org/x/tools v0.0.0-20200828161849-5deb26317202
 )
diff --git a/go.sum b/go.sum
index f56cf0cb..77cea1bb 100644
--- a/go.sum
+++ b/go.sum
@@ -1,29 +1,34 @@
-github.com/google/go-cmp v0.5.1 h1:JFrFEBb2xKufg6XkJsJr+WbKb4FQlURi5RUcBveYu9k=
-github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
+github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
-github.com/rogpeppe/go-internal v1.6.0 h1:IZRgg4sfrDH7nsAD1Y/Nwj+GzIfEwpJSLjCaNC3SbsI=
-github.com/rogpeppe/go-internal v1.6.0/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
-github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+github.com/rogpeppe/go-internal v1.6.1 h1:/FiVV8dS/e+YqF2JvO3yXRFbBLTIuSDkuC7aBOAvL+k=
+github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/mod v0.3.1-0.20200828183125-ce943fd02449 h1:xUIPaMhvROX9dhPvRCenIJtU78+lbEenGbgqB5hfHCQ=
+golang.org/x/mod v0.3.1-0.20200828183125-ce943fd02449/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.0.0-20200622203043-20e05c1c8ffa h1:mMXQKlWCw9mIWgVLLfiycDZjMHMMYqiuakI4E/l2xcA=
-golang.org/x/tools v0.0.0-20200622203043-20e05c1c8ffa/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
+golang.org/x/tools v0.0.0-20200828161849-5deb26317202 h1:DrWbY9UUFi/sl/3HkNVoBjDbGfIPZZfgoGsGxOL1EU8=
+golang.org/x/tools v0.0.0-20200828161849-5deb26317202/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
diff --git a/gointernal.go b/gointernal.go
deleted file mode 100644
index 47a854cd..00000000
--- a/gointernal.go
+++ /dev/null
@@ -1,49 +0,0 @@
-package main
-
-import (
-	"path"
-	"strings"
-)
-
-// All source code in this file is copied from the main Go repository, licensed
-// under the same license as this project, BSD-3-Clause.
-
-func GlobsMatchPath(globs, target string) bool {
-	for globs != "" {
-		// Extract next non-empty glob in comma-separated list.
-		var glob string
-		if i := strings.Index(globs, ","); i >= 0 {
-			glob, globs = globs[:i], globs[i+1:]
-		} else {
-			glob, globs = globs, ""
-		}
-		if glob == "" {
-			continue
-		}
-
-		// A glob with N+1 path elements (N slashes) needs to be matched
-		// against the first N+1 path elements of target,
-		// which end just before the N+1'th slash.
-		n := strings.Count(glob, "/")
-		prefix := target
-		// Walk target, counting slashes, truncating at the N+1'th slash.
-		for i := 0; i < len(target); i++ {
-			if target[i] == '/' {
-				if n == 0 {
-					prefix = target[:i]
-					break
-				}
-				n--
-			}
-		}
-		if n > 0 {
-			// Not enough prefix elements.
-			continue
-		}
-		matched, _ := path.Match(glob, prefix)
-		if matched {
-			return true
-		}
-	}
-	return false
-}
diff --git a/main.go b/main.go
index 58c2e53b..3a0bed5d 100644
--- a/main.go
+++ b/main.go
@@ -29,7 +29,9 @@ import (
 	"runtime"
 	"strings"
 
+	"golang.org/x/mod/module"
 	"golang.org/x/tools/go/ast/astutil"
+
 	"mvdan.cc/garble/internal/literals"
 )
 
@@ -585,7 +587,7 @@ const privateBlacklist = "runtime,internal/cpu,internal/bytealg"
 // To allow using garble without GOPRIVATE for standalone main packages, it will
 // default to not matching standard library packages.
 func isPrivate(path string) bool {
-	if GlobsMatchPath(privateBlacklist, path) {
+	if module.MatchPrefixPatterns(privateBlacklist, path) {
 		return false
 	}
 	if path == "main" || path == "command-line-arguments" || strings.HasPrefix(path, "plugin/unnamed") {
@@ -594,7 +596,7 @@ func isPrivate(path string) bool {
 		// the compiler.
 		return true
 	}
-	return GlobsMatchPath(envGoPrivate, path)
+	return module.MatchPrefixPatterns(envGoPrivate, path)
 }
 
 func readBuildIDs(flags []string) error {