diff --git a/requirements.in b/requirements.in
index 26637537..43fc713d 100644
--- a/requirements.in
+++ b/requirements.in
@@ -21,7 +21,7 @@ CommonMark
 bleach
 xmltodict
 rangedict
-openpyxl
+openpyxl==3.1.2
 gunicorn
 lxml<5
 
diff --git a/requirements.txt b/requirements.txt
index 0df59b68..db930ac3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -99,7 +99,7 @@ markupsafe==2.1.5
     # via werkzeug
 odfpy==1.4.1
     # via flattentool
-openpyxl==3.1.5
+openpyxl==3.1.2
     # via
     #   -r requirements.in
     #   flattentool
diff --git a/requirements_dev.txt b/requirements_dev.txt
index 8d42dc60..bb427b63 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -180,7 +180,7 @@ odfpy==1.4.1
     #   flattentool
 odsc-default-sphinx-theme==0.0.1
     # via -r requirements_dev.in
-openpyxl==3.1.5
+openpyxl==3.1.2
     # via
     #   -r requirements.txt
     #   flattentool