diff --git a/perceiver/requirements.txt b/perceiver/requirements.txt
index 813211e..dae77bd 100644
--- a/perceiver/requirements.txt
+++ b/perceiver/requirements.txt
@@ -2,17 +2,17 @@ absl-py==0.13.0
 dill==0.3.4
 dm-haiku==0.0.4
 einops==0.3.0
-flatbuffers==2.0
+flatbuffers~=1.12.0
 imageio==2.9.0
 immutabledict==2.0.0
 jaxline==0.0.3
-numpy==1.21.0
+numpy~=1.19.2
 opencv-python==4.5.2.54
 opt-einsum==3.3.0
 optax==0.0.9
 Pillow==8.3.1
 scipy==1.7.0
-six==1.16.0
+six~=1.15.0
 tabulate==0.8.9
 tensorflow==2.5.0
 tensorflow-addons==0.13.0