diff --git a/internal/lsp/general.go b/internal/lsp/general.go
index 6603e47c12..7165db9b89 100644
--- a/internal/lsp/general.go
+++ b/internal/lsp/general.go
@@ -96,7 +96,24 @@ func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitializ
 		}
 	}
 
-	goplsVersion, err := json.Marshal(debug.VersionInfo())
+	versionInfo := debug.VersionInfo()
+
+	// golang/go#45732: Warn users who've installed sergi/go-diff@v1.2.0, since
+	// it will corrupt the formatting of their files.
+	for _, dep := range versionInfo.Deps {
+		if dep.Path == "github.com/sergi/go-diff" && dep.Version == "v1.2.0" {
+			if err := s.eventuallyShowMessage(ctx, &protocol.ShowMessageParams{
+				Message: `It looks like you have a bad gopls installation.
+Please reinstall gopls by running 'GO111MODULE=on go get golang.org/x/tools/gopls@latest'.
+See https://github.com/golang/go/issues/45732 for more information.`,
+				Type: protocol.Error,
+			}); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	goplsVersion, err := json.Marshal(versionInfo)
 	if err != nil {
 		return nil, err
 	}