diff --git a/requirements.txt b/requirements.txt
index 4077583..f282086 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-numpy
+numpy<1.19
 scipy
 cached_property
 lacecore[obj]==0.4.1
diff --git a/requirements_doc.txt b/requirements_doc.txt
index 301ca1d..48324c4 100644
--- a/requirements_doc.txt
+++ b/requirements_doc.txt
@@ -1,5 +1,5 @@
 # Imported from code.
-numpy
+numpy<1.19
 cached_property
 lacecore[obj]==0.4.1
 meshlab-pickedpoints==1.0.0