diff --git a/go/loader/loader.go b/go/loader/loader.go
index 709bd20d..cf5d914e 100644
--- a/go/loader/loader.go
+++ b/go/loader/loader.go
@@ -25,16 +25,17 @@
 //      // See FromArgsUsage for help.
 //      rest, err := conf.FromArgs(os.Args[1:])
 //
-//      // Parse the specified files and create an ad-hoc package.
+//      // Parse the specified files and create an ad-hoc package with path "foo".
 //      // All files must have the same 'package' declaration.
-//      err := conf.CreateFromFilenames("foo.go", "bar.go")
+//      err := conf.CreateFromFilenames("foo", "foo.go", "bar.go")
 //
-//      // Create an ad-hoc package from the specified already-parsed files.
+//      // Create an ad-hoc package with path "foo" from
+//      // the specified already-parsed files.
 //      // All ASTs must have the same 'package' declaration.
-//      err := conf.CreateFromFiles(parsedFiles)
+//      err := conf.CreateFromFiles("foo", parsedFiles)
 //
 //      // Add "runtime" to the set of packages to be loaded.
-//      err := conf.Import("runtime")
+//      conf.Import("runtime")
 //
 //      // Adds "fmt" and "fmt_test" to the set of packages
 //      // to be loaded.  "fmt" will include *_test.go files.
@@ -92,6 +93,8 @@ package loader
 //   (*Config).CreateFromFiles has a nasty precondition.
 // - Ideally some of this logic would move under the umbrella of
 //   go/types; see bug 7114.
+// - s/path/importPath/g to avoid ambiguity with other meanings of
+//   "path": a file name, a colon-separated directory list.
 
 import (
 	"errors"
@@ -157,13 +160,15 @@ type Config struct {
 	Build *build.Context
 
 	// CreatePkgs specifies a list of non-importable initial
-	// packages to create.  Each element is a list of parsed files
-	// to be type-checked into a new package whose name is taken
-	// from ast.File.Package.
+	// packages to create.  Each element specifies a list of
+	// parsed files to be type-checked into a new package, and a
+	// path for that package.  If the path is "", the package's
+	// name will be used instead.  The path needn't be globally
+	// unique.
 	//
 	// The resulting packages will appear in the corresponding
 	// elements of the Program.Created slice.
-	CreatePkgs [][]*ast.File
+	CreatePkgs []CreatePkg
 
 	// ImportPkgs specifies a set of initial packages to load from
 	// source.  The map keys are package import paths, used to
@@ -176,6 +181,11 @@ type Config struct {
 	ImportPkgs map[string]bool
 }
 
+type CreatePkg struct {
+	Path  string
+	Files []*ast.File
+}
+
 // A Program is a Go program loaded from source or binary
 // as specified by a Config.
 type Program struct {
@@ -224,9 +234,8 @@ Each argument may take one of two forms:
 1. A comma-separated list of *.go source files.
 
    All of the specified files are loaded, parsed and type-checked
-   as a single package.  The name of the package is taken from the
-   files' package declarations, which must all be equal.  All the
-   files must belong to the same directory.
+   as a single package.
+   All the files must belong to the same directory.
 
 2. An import path.
 
@@ -268,8 +277,8 @@ func (conf *Config) FromArgs(args []string) (rest []string, err error) {
 
 		if strings.HasSuffix(arg, ".go") {
 			// Assume arg is a comma-separated list of *.go files
-			// comprising a single package.
-			err = conf.CreateFromFilenames(strings.Split(arg, ",")...)
+			// denoting a single ad-hoc package.
+			err = conf.CreateFromFilenames("", strings.Split(arg, ",")...)
 		} else {
 			// Assume arg is a directory name denoting a
 			// package, perhaps plus an external test
@@ -291,27 +300,27 @@ func (conf *Config) FromArgs(args []string) (rest []string, err error) {
 // specified *.go files and adds a package entry for them to
 // conf.CreatePkgs.
 //
-func (conf *Config) CreateFromFilenames(filenames ...string) error {
+func (conf *Config) CreateFromFilenames(path string, filenames ...string) error {
 	files, err := parseFiles(conf.fset(), ".", filenames...)
 	if err != nil {
 		return err
 	}
 
-	conf.CreateFromFiles(files...)
+	conf.CreateFromFiles(path, files...)
 	return nil
 }
 
 // CreateFromFiles is a convenience function that adds a CreatePkgs
-// entry for the specified parsed files.
+// entry to create package of the specified path and parsed files.
 //
 // Precondition: conf.Fset is non-nil and was the fileset used to parse
 // the files.  (e.g. the files came from conf.ParseFile().)
 //
-func (conf *Config) CreateFromFiles(files ...*ast.File) {
+func (conf *Config) CreateFromFiles(path string, files ...*ast.File) {
 	if conf.Fset == nil {
 		panic("nil Fset")
 	}
-	conf.CreatePkgs = append(conf.CreatePkgs, files)
+	conf.CreatePkgs = append(conf.CreatePkgs, CreatePkg{path, files})
 }
 
 // ImportWithTests is a convenience function that adds path to
@@ -320,7 +329,7 @@ func (conf *Config) CreateFromFiles(files ...*ast.File) {
 // its directory that contain a "package x" (not "package x_test")
 // declaration.
 //
-// In addition, if any *_test.go files contain a "package <path>_test"
+// In addition, if any *_test.go files contain a "package x_test"
 // declaration, an additional package comprising just those files will
 // be added to CreatePkgs.
 //
@@ -344,7 +353,7 @@ func (conf *Config) ImportWithTests(path string) error {
 		return err
 	}
 	if len(xtestFiles) > 0 {
-		conf.CreateFromFiles(xtestFiles...)
+		conf.CreateFromFiles(path+"_test", xtestFiles...)
 	}
 
 	// Mark the non-xtest package for augmentation with
@@ -450,14 +459,12 @@ func (conf *Config) Load() (*Program, error) {
 		prog.Imported[path] = info
 	}
 
-	for _, files := range conf.CreatePkgs {
-		pkgname, err := packageName(files, conf.Fset)
-		if err != nil {
-			return nil, err
+	for _, create := range conf.CreatePkgs {
+		path := create.Path
+		if create.Path == "" && len(create.Files) > 0 {
+			path = create.Files[0].Name.Name
 		}
-		// TODO(adonovan): pkgnames are not unique, but the
-		// typechecker assumes they are in its Id() logic.
-		prog.Created = append(prog.Created, imp.createPackage(pkgname, files...))
+		prog.Created = append(prog.Created, imp.createPackage(path, create.Files...))
 	}
 
 	if len(prog.Imported)+len(prog.Created) == 0 {
diff --git a/go/loader/source_test.go b/go/loader/source_test.go
index 8a63ea51..1c5653ec 100644
--- a/go/loader/source_test.go
+++ b/go/loader/source_test.go
@@ -93,7 +93,7 @@ func TestEnclosingFunction(t *testing.T) {
 			continue
 		}
 
-		conf.CreateFromFiles(f)
+		conf.CreateFromFiles("main", f)
 
 		iprog, err := conf.Load()
 		if err != nil {
diff --git a/go/loader/util.go b/go/loader/util.go
index e17c8a42..164ee66a 100644
--- a/go/loader/util.go
+++ b/go/loader/util.go
@@ -4,11 +4,7 @@
 
 package loader
 
-// This file defines various utility functions exposed by the package
-// and used by it.
-
 import (
-	"fmt"
 	"go/ast"
 	"go/build"
 	"go/parser"
@@ -104,25 +100,6 @@ func unreachable() {
 	panic("unreachable")
 }
 
-func packageName(files []*ast.File, fset *token.FileSet) (string, error) {
-	if len(files) == 0 {
-		return "", fmt.Errorf("no files in package")
-	}
-	// Take the package name from the 'package decl' in each file,
-	// all of which must match.
-	pkgname := files[0].Name.Name
-	for _, file := range files[1:] {
-		if pn := file.Name.Name; pn != pkgname {
-			err := fmt.Errorf("can't load package: found packages %s (%s) and %s (%s)",
-				pkgname, filename(files[0], fset),
-				pn, filename(file, fset))
-			return "", err
-		}
-		// TODO(adonovan): check dirnames are equal, like 'go build' does.
-	}
-	return pkgname, nil
-}
-
 // TODO(adonovan): make this a method: func (*token.File) Contains(token.Pos)
 func tokenFileContainsPos(f *token.File, pos token.Pos) bool {
 	p := int(pos)
diff --git a/go/pointer/example_test.go b/go/pointer/example_test.go
index db625783..07ec3a8c 100644
--- a/go/pointer/example_test.go
+++ b/go/pointer/example_test.go
@@ -49,7 +49,7 @@ func main() {
 	}
 
 	// Create single-file main package and import its dependencies.
-	conf.CreateFromFiles(file)
+	conf.CreateFromFiles("main", file)
 
 	iprog, err := conf.Load()
 	if err != nil {
diff --git a/go/pointer/pointer_test.go b/go/pointer/pointer_test.go
index daf8c184..6e00f6f1 100644
--- a/go/pointer/pointer_test.go
+++ b/go/pointer/pointer_test.go
@@ -161,7 +161,7 @@ func doOneInput(input, filename string) bool {
 	}
 
 	// Create single-file main package and import its dependencies.
-	conf.CreateFromFiles(f)
+	conf.CreateFromFiles("main", f)
 	iprog, err := conf.Load()
 	if err != nil {
 		fmt.Println(err)
diff --git a/go/pointer/testdata/a_test.go b/go/pointer/testdata/a_test.go
index 828dcb6f..3baa9ac7 100644
--- a/go/pointer/testdata/a_test.go
+++ b/go/pointer/testdata/a_test.go
@@ -11,7 +11,7 @@ import "testing"
 
 func log(f func(*testing.T)) {
 	// The PTS of f is the set of called tests.  TestingQuux is not present.
-	print(f) // @pointsto a.Test | a.TestFoo
+	print(f) // @pointsto main.Test | main.TestFoo
 }
 
 func Test(t *testing.T) {
@@ -36,7 +36,7 @@ func ExampleBar() {
 }
 
 // Excludes TestingQuux.
-// @calls testing.tRunner -> a.Test
-// @calls testing.tRunner -> a.TestFoo
-// @calls testing.runExample -> a.ExampleBar
-// @calls (*testing.B).runN -> a.BenchmarkFoo
+// @calls testing.tRunner -> main.Test
+// @calls testing.tRunner -> main.TestFoo
+// @calls testing.runExample -> main.ExampleBar
+// @calls (*testing.B).runN -> main.BenchmarkFoo
diff --git a/go/ssa/builder_test.go b/go/ssa/builder_test.go
index 6421cb87..03d77a04 100644
--- a/go/ssa/builder_test.go
+++ b/go/ssa/builder_test.go
@@ -47,7 +47,7 @@ func main() {
 		t.Error(err)
 		return
 	}
-	conf.CreateFromFiles(f)
+	conf.CreateFromFiles("main", f)
 
 	iprog, err := conf.Load()
 	if err != nil {
@@ -212,7 +212,7 @@ func TestTypesWithMethodSets(t *testing.T) {
 			t.Errorf("test %d: %s", i, err)
 			continue
 		}
-		conf.CreateFromFiles(f)
+		conf.CreateFromFiles("p", f)
 
 		iprog, err := conf.Load()
 		if err != nil {
diff --git a/go/ssa/example_test.go b/go/ssa/example_test.go
index d294ce2a..985a5219 100644
--- a/go/ssa/example_test.go
+++ b/go/ssa/example_test.go
@@ -50,7 +50,7 @@ func main() {
 	}
 
 	// Create single-file main package.
-	conf.CreateFromFiles(file)
+	conf.CreateFromFiles("main", file)
 
 	// Load the main package and its dependencies.
 	iprog, err := conf.Load()
diff --git a/go/ssa/interp/interp_test.go b/go/ssa/interp/interp_test.go
index 4c1d4352..60dc9c3e 100644
--- a/go/ssa/interp/interp_test.go
+++ b/go/ssa/interp/interp_test.go
@@ -171,7 +171,7 @@ func run(t *testing.T, dir, input string, success successPredicate) bool {
 	conf := loader.Config{SourceImports: true}
 	// TODO(adonovan): add the following packages' tests, which pass:
 	// "flag", "unicode", "unicode/utf8", "testing", "log", "path".
-	if err := conf.CreateFromFilenames(inputs...); err != nil {
+	if err := conf.CreateFromFilenames("", inputs...); err != nil {
 		t.Errorf("CreateFromFilenames(%s) failed: %s", inputs, err)
 		return false
 	}
@@ -319,7 +319,7 @@ func TestTestmainPackage(t *testing.T) {
 // CreateTestMainPackage should return nil if there were no tests.
 func TestNullTestmainPackage(t *testing.T) {
 	var conf loader.Config
-	if err := conf.CreateFromFilenames("testdata/b_test.go"); err != nil {
+	if err := conf.CreateFromFilenames("", "testdata/b_test.go"); err != nil {
 		t.Fatalf("ParseFile failed: %s", err)
 	}
 	iprog, err := conf.Load()
diff --git a/go/ssa/source_test.go b/go/ssa/source_test.go
index 54155044..0f37f843 100644
--- a/go/ssa/source_test.go
+++ b/go/ssa/source_test.go
@@ -30,7 +30,7 @@ func TestObjValueLookup(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	conf.CreateFromFiles(f)
+	conf.CreateFromFiles("main", f)
 
 	// Maps each var Ident (represented "name:linenum") to the
 	// kind of ssa.Value we expect (represented "Constant", "&Alloc").
@@ -194,7 +194,7 @@ func TestValueForExpr(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	conf.CreateFromFiles(f)
+	conf.CreateFromFiles("main", f)
 
 	iprog, err := conf.Load()
 	if err != nil {
diff --git a/go/ssa/ssautil/switch_test.go b/go/ssa/ssautil/switch_test.go
index 5a4b38ff..a68f4644 100644
--- a/go/ssa/ssautil/switch_test.go
+++ b/go/ssa/ssautil/switch_test.go
@@ -22,7 +22,7 @@ func TestSwitches(t *testing.T) {
 		return
 	}
 
-	conf.CreateFromFiles(f)
+	conf.CreateFromFiles("main", f)
 	iprog, err := conf.Load()
 	if err != nil {
 		t.Error(err)
diff --git a/oracle/oracle_test.go b/oracle/oracle_test.go
index 37355646..19b4edb3 100644
--- a/oracle/oracle_test.go
+++ b/oracle/oracle_test.go
@@ -261,7 +261,7 @@ func TestMultipleQueries(t *testing.T) {
 	buildContext.GOPATH = "testdata"
 	conf := loader.Config{Build: &buildContext}
 	filename := "testdata/src/main/multi.go"
-	conf.CreateFromFilenames(filename)
+	conf.CreateFromFilenames("", filename)
 	iprog, err := conf.Load()
 	if err != nil {
 		t.Fatalf("Load failed: %s", err)