diff --git a/cibuildwheel/resources/constraints-python27.txt b/cibuildwheel/resources/constraints-python27.txt
index aca7c901..c9c443af 100644
--- a/cibuildwheel/resources/constraints-python27.txt
+++ b/cibuildwheel/resources/constraints-python27.txt
@@ -37,7 +37,7 @@ six==1.15.0
     #   virtualenv
 typing==3.7.4.3
     # via importlib-resources
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints-python35.txt b/cibuildwheel/resources/constraints-python35.txt
index 6790cdc2..b0df8f2e 100644
--- a/cibuildwheel/resources/constraints-python35.txt
+++ b/cibuildwheel/resources/constraints-python35.txt
@@ -18,7 +18,7 @@ importlib-resources==3.2.1
     # via virtualenv
 six==1.15.0
     # via virtualenv
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints-python36.txt b/cibuildwheel/resources/constraints-python36.txt
index ab2df3c3..e510460e 100644
--- a/cibuildwheel/resources/constraints-python36.txt
+++ b/cibuildwheel/resources/constraints-python36.txt
@@ -14,13 +14,13 @@ filelock==3.0.12
     # via virtualenv
 importlib-metadata==3.4.0
     # via virtualenv
-importlib-resources==5.0.0
+importlib-resources==5.1.0
     # via virtualenv
 six==1.15.0
     # via virtualenv
 typing-extensions==3.7.4.3
     # via importlib-metadata
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints-python37.txt b/cibuildwheel/resources/constraints-python37.txt
index 04fe068c..181f65ee 100644
--- a/cibuildwheel/resources/constraints-python37.txt
+++ b/cibuildwheel/resources/constraints-python37.txt
@@ -18,7 +18,7 @@ six==1.15.0
     # via virtualenv
 typing-extensions==3.7.4.3
     # via importlib-metadata
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints-python38.txt b/cibuildwheel/resources/constraints-python38.txt
index 991ebad6..d31a4324 100644
--- a/cibuildwheel/resources/constraints-python38.txt
+++ b/cibuildwheel/resources/constraints-python38.txt
@@ -14,7 +14,7 @@ filelock==3.0.12
     # via virtualenv
 six==1.15.0
     # via virtualenv
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints-python39.txt b/cibuildwheel/resources/constraints-python39.txt
index 991ebad6..d31a4324 100644
--- a/cibuildwheel/resources/constraints-python39.txt
+++ b/cibuildwheel/resources/constraints-python39.txt
@@ -14,7 +14,7 @@ filelock==3.0.12
     # via virtualenv
 six==1.15.0
     # via virtualenv
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via
diff --git a/cibuildwheel/resources/constraints.txt b/cibuildwheel/resources/constraints.txt
index 991ebad6..d31a4324 100644
--- a/cibuildwheel/resources/constraints.txt
+++ b/cibuildwheel/resources/constraints.txt
@@ -14,7 +14,7 @@ filelock==3.0.12
     # via virtualenv
 six==1.15.0
     # via virtualenv
-virtualenv==20.3.1
+virtualenv==20.4.0
     # via -r cibuildwheel/resources/constraints.in
 wheel==0.36.2
     # via