diff --git a/gps/prune.go b/gps/prune.go
index aa8671c414..e3f48e3cd7 100644
--- a/gps/prune.go
+++ b/gps/prune.go
@@ -333,22 +333,36 @@ func isPreservedFile(name string) bool {
 	return false
 }
 
-// pruneGoTestFiles deletes all Go test files (*_test.go) in fsState.
+// pruneGoTestFiles deletes all Go test files (*_test.go and testdata/**/*)
+// in fsState.
 func pruneGoTestFiles(fsState filesystemState) error {
-	toDelete := make([]string, 0, len(fsState.files)/2)
+	filesToDelete := make([]string, 0, len(fsState.files)/2)
+	dirsToDelete := make([]string, 0)
 
 	for _, path := range fsState.files {
 		if strings.HasSuffix(path, "_test.go") {
-			toDelete = append(toDelete, filepath.Join(fsState.root, path))
+			filesToDelete = append(filesToDelete, filepath.Join(fsState.root, path))
 		}
 	}
 
-	for _, path := range toDelete {
+	for _, path := range fsState.dirs {
+		if filepath.Base(path) == "testdata" {
+			dirsToDelete = append(dirsToDelete, filepath.Join(fsState.root, path))
+		}
+	}
+
+	for _, path := range filesToDelete {
 		if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
 			return err
 		}
 	}
 
+	for _, path := range dirsToDelete {
+		if err := os.RemoveAll(path); err != nil && !os.IsNotExist(err) {
+			return err
+		}
+	}
+
 	return nil
 }
 
diff --git a/gps/prune_test.go b/gps/prune_test.go
index 0d202a8cac..f653e15aa3 100644
--- a/gps/prune_test.go
+++ b/gps/prune_test.go
@@ -426,6 +426,31 @@ func TestPruneGoTestFiles(t *testing.T) {
 			},
 			false,
 		},
+		{
+			"testdata-files",
+			fsTestCase{
+				before: filesystemState{
+					dirs: []string{
+						"dir",
+						"dir/testdata",
+					},
+					files: []string{
+						"dir/main.go",
+						"dir/main_test.go",
+						"dir/testdata/foo",
+					},
+				},
+				after: filesystemState{
+					dirs: []string{
+						"dir",
+					},
+					files: []string{
+						"dir/main.go",
+					},
+				},
+			},
+			false,
+		},
 	}
 
 	for _, tc := range testcases {