diff --git a/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommand.java b/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommand.java
index 012c7ef2c6..b3ba882040 100644
--- a/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommand.java
+++ b/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommand.java
@@ -12,7 +12,7 @@ public interface ModifyCommand {
 
     void create(String toBeCreated, File file, boolean overwrite) throws IOException;
 
-    void modify(String path, File file);
+    void modify(String path, File file) throws IOException;
 
     void move(String sourcePath, String targetPath);
   }
diff --git a/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommandRequest.java b/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommandRequest.java
index 9069154951..a108a73546 100644
--- a/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommandRequest.java
+++ b/scm-core/src/main/java/sonia/scm/repository/spi/ModifyCommandRequest.java
@@ -158,7 +158,7 @@ public class ModifyCommandRequest implements Resetable, Validateable {
     }
 
     @Override
-    public void execute(ModifyCommand.Worker worker) {
+    public void execute(ModifyCommand.Worker worker) throws IOException {
       worker.modify(path, getContent());
       cleanup();
     }
diff --git a/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitModifyCommand.java b/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitModifyCommand.java
index 806f667515..d03af28e3a 100644
--- a/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitModifyCommand.java
+++ b/scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitModifyCommand.java
@@ -9,7 +9,6 @@ import org.eclipse.jgit.revwalk.RevCommit;
 import sonia.scm.BadRequestException;
 import sonia.scm.ConcurrentModificationException;
 import sonia.scm.ContextEntry;
-import sonia.scm.NotFoundException;
 import sonia.scm.repository.GitWorkdirFactory;
 import sonia.scm.repository.InternalRepositoryException;
 import sonia.scm.repository.Repository;
@@ -25,6 +24,7 @@ import java.util.Optional;
 import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
 import static sonia.scm.AlreadyExistsException.alreadyExists;
 import static sonia.scm.ContextEntry.ContextBuilder.entity;
+import static sonia.scm.NotFoundException.notFound;
 import static sonia.scm.ScmConstraintViolationException.Builder.doThrow;
 
 public class GitModifyCommand extends AbstractGitCommand implements ModifyCommand {
@@ -79,10 +79,10 @@ public class GitModifyCommand extends AbstractGitCommand implements ModifyComman
       Path targetFile = new File(workDir, toBeCreated).toPath();
       Files.createDirectories(targetFile.getParent());
       if (overwrite) {
-        Files.copy(file.toPath(), targetFile, REPLACE_EXISTING);
+        Files.move(file.toPath(), targetFile, REPLACE_EXISTING);
       } else {
         try {
-          Files.copy(file.toPath(), targetFile);
+          Files.move(file.toPath(), targetFile);
         } catch (FileAlreadyExistsException e) {
           throw alreadyExists(createFileContext(toBeCreated));
         }
@@ -94,13 +94,28 @@ public class GitModifyCommand extends AbstractGitCommand implements ModifyComman
       }
     }
 
+    @Override
+    public void modify(String path, File file) throws IOException {
+      Path targetFile = new File(workDir, path).toPath();
+      Files.createDirectories(targetFile.getParent());
+      if (!targetFile.toFile().exists()) {
+        throw notFound(createFileContext(path));
+      }
+      Files.move(file.toPath(), targetFile, REPLACE_EXISTING);
+      try {
+        getClone().add().addFilepattern(path).call();
+      } catch (GitAPIException e) {
+        throwInternalRepositoryException("could not add new file to index", e);
+      }
+    }
+
     @Override
     public void delete(String toBeDeleted) throws IOException {
       Path fileToBeDeleted = new File(workDir, toBeDeleted).toPath();
       try {
         Files.delete(fileToBeDeleted);
       } catch (NoSuchFileException e) {
-        throw NotFoundException.notFound(createFileContext(toBeDeleted));
+        throw notFound(createFileContext(toBeDeleted));
       }
       try {
         getClone().rm().addFilepattern(toBeDeleted).call();
@@ -109,8 +124,8 @@ public class GitModifyCommand extends AbstractGitCommand implements ModifyComman
       }
     }
 
-    private ContextEntry.ContextBuilder createFileContext(String toBeDeleted) {
-      ContextEntry.ContextBuilder contextBuilder = entity("file", toBeDeleted);
+    private ContextEntry.ContextBuilder createFileContext(String path) {
+      ContextEntry.ContextBuilder contextBuilder = entity("file", path);
       if (!StringUtils.isEmpty(request.getBranch())) {
         contextBuilder.in("branch", request.getBranch());
       }
@@ -118,11 +133,6 @@ public class GitModifyCommand extends AbstractGitCommand implements ModifyComman
       return contextBuilder;
     }
 
-    @Override
-    public void modify(String path, File file) {
-
-    }
-
     @Override
     public void move(String sourcePath, String targetPath) {
 
diff --git a/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitModifyCommandTest.java b/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitModifyCommandTest.java
index 1a9bd5e04a..9916272596 100644
--- a/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitModifyCommandTest.java
+++ b/scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitModifyCommandTest.java
@@ -129,6 +129,38 @@ public class GitModifyCommandTest extends AbstractGitCommandTestBase {
     assertInTree(assertions);
   }
 
+  @Test
+  public void shouldModifyExistingFile() throws IOException, GitAPIException {
+    File newFile = Files.write(temporaryFolder.newFile().toPath(), "new content".getBytes()).toFile();
+
+    GitModifyCommand command = createCommand();
+
+    ModifyCommandRequest request = new ModifyCommandRequest();
+    request.setCommitMessage("test commit");
+    request.addRequest(new ModifyCommandRequest.ModifyFileRequest("a.txt", newFile));
+    request.setAuthor(new Person("Dirk Gently", "dirk@holistic.det"));
+
+    command.execute(request);
+
+    TreeAssertions assertions = canonicalTreeParser -> assertThat(canonicalTreeParser.findFile("a.txt")).isTrue();
+
+    assertInTree(assertions);
+  }
+
+  @Test(expected = NotFoundException.class)
+  public void shouldFailIfFileToModifyDoesNotExist() throws IOException {
+    File newFile = Files.write(temporaryFolder.newFile().toPath(), "new content".getBytes()).toFile();
+
+    GitModifyCommand command = createCommand();
+
+    ModifyCommandRequest request = new ModifyCommandRequest();
+    request.setCommitMessage("test commit");
+    request.addRequest(new ModifyCommandRequest.ModifyFileRequest("no.such.file", newFile));
+    request.setAuthor(new Person("Dirk Gently", "dirk@holistic.det"));
+
+    command.execute(request);
+  }
+
   @Test(expected = BadRequestException.class)
   public void shouldFailIfNoChangesMade() throws IOException {
     File newFile = Files.write(temporaryFolder.newFile().toPath(), "b\n".getBytes()).toFile();