diff --git a/packages/tsdl/tsdl.0.9.1/opam b/packages/tsdl/tsdl.0.9.1/opam
index b75f0d2e066e..1482c8b58893 100644
--- a/packages/tsdl/tsdl.0.9.1/opam
+++ b/packages/tsdl/tsdl.0.9.1/opam
@@ -15,7 +15,7 @@ depends: [
   "topkg" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[
diff --git a/packages/tsdl/tsdl.0.9.2/opam b/packages/tsdl/tsdl.0.9.2/opam
index c22035d2c5f7..46b8531c9d44 100644
--- a/packages/tsdl/tsdl.0.9.2/opam
+++ b/packages/tsdl/tsdl.0.9.2/opam
@@ -16,7 +16,7 @@ depends: [
   "ocb-stubblr" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[
diff --git a/packages/tsdl/tsdl.0.9.3/opam b/packages/tsdl/tsdl.0.9.3/opam
index 1ecc7ab450f4..f733ee8821db 100644
--- a/packages/tsdl/tsdl.0.9.3/opam
+++ b/packages/tsdl/tsdl.0.9.3/opam
@@ -16,7 +16,7 @@ depends: [
   "ocb-stubblr" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[
diff --git a/packages/tsdl/tsdl.0.9.4/opam b/packages/tsdl/tsdl.0.9.4/opam
index c37586b4d7c1..9bfd921e1108 100644
--- a/packages/tsdl/tsdl.0.9.4/opam
+++ b/packages/tsdl/tsdl.0.9.4/opam
@@ -16,7 +16,7 @@ depends: [
   "ocb-stubblr" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[
diff --git a/packages/tsdl/tsdl.0.9.5/opam b/packages/tsdl/tsdl.0.9.5/opam
index c8a36f2b00d8..c9a45c0aabeb 100644
--- a/packages/tsdl/tsdl.0.9.5/opam
+++ b/packages/tsdl/tsdl.0.9.5/opam
@@ -16,7 +16,7 @@ depends: [
   "ocb-stubblr" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[
diff --git a/packages/tsdl/tsdl.0.9.6/opam b/packages/tsdl/tsdl.0.9.6/opam
index ed2c00096d58..637d3a0d3315 100644
--- a/packages/tsdl/tsdl.0.9.6/opam
+++ b/packages/tsdl/tsdl.0.9.6/opam
@@ -16,7 +16,7 @@ depends: [
   "ocb-stubblr" {build}
   "conf-sdl2"
   "result" {< "1.5"}
-  "ctypes" {>= "0.9.0"}
+  "ctypes" {>= "0.9.0" & < "0.21.0"}
   "ctypes-foreign"
 ]
 build: [[