diff --git a/.gitmodules b/.gitmodules
index 5f254536..7dc47876 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,3 @@
 [submodule "examples/cryptol-specs"]
 	path = examples/cryptol-specs
 	url = https://github.com/GaloisInc/cryptol-specs.git
-[submodule "dependencies/what4"]
-	path = dependencies/what4
-	url = https://github.com/GaloisInc/what4.git
diff --git a/cabal.project b/cabal.project
index 8e43e3e1..7a74a0ab 100644
--- a/cabal.project
+++ b/cabal.project
@@ -1,6 +1,3 @@
 packages:
     cryptol.cabal
     tests
-
-optional-packages:
-    dependencies/what4/what4
diff --git a/cryptol.cabal b/cryptol.cabal
index 4fcb21b4..9260a0d1 100644
--- a/cryptol.cabal
+++ b/cryptol.cabal
@@ -73,7 +73,7 @@ library
                        mtl               >= 2.2.1,
                        time              >= 1.6.0.1,
                        panic             >= 0.3,
-                       what4             >= 0.1
+                       what4             >= 1.0 && < 1.1
 
   Build-tools:         alex, happy
   hs-source-dirs:      src
diff --git a/dependencies/what4 b/dependencies/what4
deleted file mode 160000
index 28125bcf..00000000
--- a/dependencies/what4
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 28125bcf53378917341f43cb717f6cded3f22287