diff --git a/optional-requirements.txt b/optional-requirements.txt
index dabbd08d..85a3d5f0 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -37,7 +37,7 @@ beautifulsoup4>=4.0.1,<4.12.0
 cchardet>=2.0.0,<2.2.0
 
 # Comics
-natsort>=2.2.0,<8.3.0
+natsort>=2.2.0,<8.4.0
 comicapi>=2.2.0,<2.3.0
 
 # Kobo integration
diff --git a/requirements.txt b/requirements.txt
index 1eaffa38..159fccb9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,9 +7,9 @@ Flask-Principal>=0.3.2,<0.5.1
 backports_abc>=0.4
 Flask>=1.0.2,<2.3.0
 iso-639>=0.4.5,<0.5.0
-PyPDF==3.4.0
+PyPDF>=3.0.0,<3.6.0
 pytz>=2016.10
-requests>=2.11.1,<2.28.0
+requests>=2.11.1,<2.29.0
 SQLAlchemy>=1.3.0,<2.0.0
 tornado>=4.1,<6.3
 Wand>=0.4.4,<0.7.0
@@ -18,4 +18,4 @@ lxml>=3.8.0,<5.0.0
 flask-wtf>=0.14.2,<1.2.0
 chardet>=3.0.0,<4.1.0
 advocate>=1.0.0,<1.1.0
-Flask-Limiter>=2.3.0,<3.3.0
+Flask-Limiter>=2.3.0,<3.4.0