diff --git a/gopls/internal/regtest/diagnostics_test.go b/gopls/internal/regtest/diagnostics_test.go
index 8a7008ab2a..74687b81fc 100644
--- a/gopls/internal/regtest/diagnostics_test.go
+++ b/gopls/internal/regtest/diagnostics_test.go
@@ -1557,3 +1557,40 @@ import _ "mod.com/triple/a"
 		)
 	})
 }
+
+func TestBadImport(t *testing.T) {
+	testenv.NeedsGo1Point(t, 14)
+
+	const mod = `
+-- go.mod --
+module mod.com
+
+go 1.12
+-- main.go --
+package main
+
+import (
+	_ "nosuchpkg"
+)
+`
+	t.Run("module", func(t *testing.T) {
+		run(t, mod, func(t *testing.T, env *Env) {
+			env.Await(
+				env.DiagnosticAtRegexpWithMessage("main.go", `"nosuchpkg"`, `could not import nosuchpkg (no required module provides package "nosuchpkg"`),
+			)
+		})
+	})
+	t.Run("GOPATH", func(t *testing.T) {
+		withOptions(
+			InGOPATH(),
+			EditorConfig{
+				Env: map[string]string{"GO111MODULE": "off"},
+			},
+			WithModes(WithoutExperiments),
+		).run(t, mod, func(t *testing.T, env *Env) {
+			env.Await(
+				env.DiagnosticAtRegexpWithMessage("main.go", `"nosuchpkg"`, `cannot find package "nosuchpkg" in any of`),
+			)
+		})
+	})
+}
diff --git a/internal/lsp/cache/check.go b/internal/lsp/cache/check.go
index 187a39142a..1760d388c9 100644
--- a/internal/lsp/cache/check.go
+++ b/internal/lsp/cache/check.go
@@ -11,6 +11,7 @@ import (
 	"go/ast"
 	"go/types"
 	"path"
+	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -407,7 +408,7 @@ func typeCheck(ctx context.Context, snapshot *snapshot, m *metadata, mode source
 			}
 			dep := resolveImportPath(pkgPath, pkg, deps)
 			if dep == nil {
-				return nil, errors.Errorf("no package for import %s", pkgPath)
+				return nil, snapshot.missingPkgError(pkgPath)
 			}
 			if !isValidImport(m.pkgPath, dep.m.pkgPath) {
 				return nil, errors.Errorf("invalid use of internal package %s", pkgPath)
@@ -453,6 +454,24 @@ func typeCheck(ctx context.Context, snapshot *snapshot, m *metadata, mode source
 	return pkg, nil
 }
 
+// missingPkgError returns an error message for a missing package that varies
+// based on the user's workspace mode.
+func (s *snapshot) missingPkgError(pkgPath string) error {
+	if s.workspaceMode()&moduleMode != 0 {
+		return fmt.Errorf("no required module provides package %q", pkgPath)
+	}
+	gorootSrcPkg := filepath.FromSlash(filepath.Join(s.view.goroot, "src", pkgPath))
+
+	var b strings.Builder
+	b.WriteString(fmt.Sprintf("cannot find package %q in any of \n\t%s (from $GOROOT)", pkgPath, gorootSrcPkg))
+
+	for _, gopath := range strings.Split(s.view.gopath, ":") {
+		gopathSrcPkg := filepath.FromSlash(filepath.Join(gopath, "src", pkgPath))
+		b.WriteString(fmt.Sprintf("\n\t%s (from $GOPATH)", gopathSrcPkg))
+	}
+	return errors.New(b.String())
+}
+
 type extendedError struct {
 	primary     types.Error
 	secondaries []types.Error
diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index 8c682bf340..75c62ddb3f 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -119,7 +119,7 @@ type workspaceInformation struct {
 }
 
 type environmentVariables struct {
-	gocache, gopath, goprivate, gomodcache string
+	gocache, gopath, goroot, goprivate, gomodcache string
 }
 
 type workspaceMode int
@@ -784,6 +784,7 @@ func (s *Session) getGoEnv(ctx context.Context, folder string, configEnv []strin
 	vars := map[string]*string{
 		"GOCACHE":    &envVars.gocache,
 		"GOPATH":     &envVars.gopath,
+		"GOROOT":     &envVars.goroot,
 		"GOPRIVATE":  &envVars.goprivate,
 		"GOMODCACHE": &envVars.gomodcache,
 	}
diff --git a/internal/lsp/cmd/test/check.go b/internal/lsp/cmd/test/check.go
index 1e07df357b..f0e6d8fefb 100644
--- a/internal/lsp/cmd/test/check.go
+++ b/internal/lsp/cmd/test/check.go
@@ -50,10 +50,6 @@ func (r *runner) Diagnostics(t *testing.T, uri span.URI, want []*source.Diagnost
 			expect = fmt.Sprintf("%v:%v: %v", uri.Filename(), diag.Range.Start.Line+1, diag.Message)
 		}
 		expect = r.NormalizePrefix(expect)
-		// Skip the badimport test for now, until we do a better job with diagnostic ranges.
-		if strings.Contains(uri.Filename(), "badimport") {
-			continue
-		}
 		_, found := got[expect]
 		if !found {
 			t.Errorf("missing diagnostic %q, %v", expect, got)
@@ -62,10 +58,6 @@ func (r *runner) Diagnostics(t *testing.T, uri span.URI, want []*source.Diagnost
 		}
 	}
 	for extra := range got {
-		// Skip the badimport test for now, until we do a better job with diagnostic ranges.
-		if strings.Contains(extra, "badimport") {
-			continue
-		}
 		t.Errorf("extra diagnostic %q", extra)
 	}
 }
diff --git a/internal/lsp/testdata/bad/badimport.go b/internal/lsp/testdata/bad/badimport.go
deleted file mode 100644
index fefc22e464..0000000000
--- a/internal/lsp/testdata/bad/badimport.go
+++ /dev/null
@@ -1,5 +0,0 @@
-package bad
-
-import (
-	_ "nosuchpkg" //@diag("_", "compiler", "could not import nosuchpkg (no package for import nosuchpkg)", "error")
-)
diff --git a/internal/lsp/testdata/summary.txt.golden b/internal/lsp/testdata/summary.txt.golden
index 0f327f6ca5..b97325801c 100644
--- a/internal/lsp/testdata/summary.txt.golden
+++ b/internal/lsp/testdata/summary.txt.golden
@@ -8,7 +8,7 @@ DeepCompletionsCount = 5
 FuzzyCompletionsCount = 8
 RankedCompletionsCount = 158
 CaseSensitiveCompletionsCount = 4
-DiagnosticsCount = 38
+DiagnosticsCount = 37
 FoldingRangesCount = 2
 FormatCount = 6
 ImportCount = 8
diff --git a/internal/lsp/tests/util.go b/internal/lsp/tests/util.go
index 0c050d0507..9fed4deb77 100644
--- a/internal/lsp/tests/util.go
+++ b/internal/lsp/tests/util.go
@@ -129,10 +129,6 @@ func DiffDiagnostics(uri span.URI, want, got []*source.Diagnostic) string {
 		if w.Source != g.Source {
 			return summarizeDiagnostics(i, uri, want, got, "incorrect Source got %v want %v", g.Source, w.Source)
 		}
-		// Don't check the range on the badimport test.
-		if strings.Contains(uri.Filename(), "badimport") {
-			continue
-		}
 		if protocol.ComparePosition(w.Range.Start, g.Range.Start) != 0 {
 			return summarizeDiagnostics(i, uri, want, got, "incorrect Start got %v want %v", g.Range.Start, w.Range.Start)
 		}