diff --git a/.github/workflows/cabal.yml b/.github/workflows/cabal.yml
index ae9295e51..bdb41e595 100644
--- a/.github/workflows/cabal.yml
+++ b/.github/workflows/cabal.yml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ghc: ["8.10.1", "8.8.1", "8.6.5", "8.6.4", "8.6.3", "8.6.2", "8.4.4", "8.2.2", "8.0.2"]
+        ghc: ["9.0.1", "8.10.1", "8.8.1", "8.6.5", "8.6.4", "8.6.3", "8.6.2", "8.4.4", "8.2.2", "8.0.2"]
         cabal: ["3.0", "3.2"]
     env:
       CONFIG: "--enable-tests --enable-benchmarks"
diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index 470e3af33..b01b56b25 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -25,6 +25,8 @@ jobs:
     strategy:
       matrix:
         include:
+          - compiler: ghc-9.0.1
+            allow-failure: false
           - compiler: ghc-8.10.1
             allow-failure: false
           - compiler: ghc-8.8.1
diff --git a/.github/workflows/stack.yml b/.github/workflows/stack.yml
index c0f76cc06..bdc379116 100644
--- a/.github/workflows/stack.yml
+++ b/.github/workflows/stack.yml
@@ -19,8 +19,9 @@ jobs:
         - { build: stack, resolver: "lts-12"  }   # ghc-8.4.4
         - { build: stack, resolver: "lts-13"  }   # redundant because lts-14 checks ghc-8.6 already
         - { build: stack, resolver: "lts-14"  }   # ghc-8.6.5
-        - { build: stack, resolver: "lts-15"  }   # ghc-8.8.2
-        - { build: stack, resolver: "lts-16"  }   # ghc-8.10.1
+        - { build: stack, resolver: "lts-15"  }   # ghc-8.8.3
+        - { build: stack, resolver: "lts-16"  }   # ghc-8.8.4
+        - { build: stack, resolver: "lts-17"  }   # ghc-8.10.4
         # - { build: stack, resolver: ""                   }
         # use this to include any dependencies from OS package managers
         include: []
diff --git a/protolude.cabal b/protolude.cabal
index af461b57b..713f91935 100644
--- a/protolude.cabal
+++ b/protolude.cabal
@@ -29,6 +29,7 @@ tested-with:
    || ==8.6.1
    || ==8.8.1
    || ==8.10.1
+   || ==9.0.1
 
 extra-source-files:
   README.md
@@ -77,11 +78,11 @@ library
   build-depends:
       array                >=0.4  && <0.6
     , async                >=2.0  && <2.3
-    , base                 >=4.6  && <4.15
+    , base                 >=4.6  && <4.16
     , bytestring           >=0.10 && <0.11
     , containers           >=0.5  && <0.7
     , deepseq              >=1.3  && <1.5
-    , ghc-prim             >=0.3  && <0.7
+    , ghc-prim             >=0.3  && <0.8
     , hashable             >=1.2  && <1.4
     , mtl                  >=2.1  && <2.3
     , mtl-compat           >=0.2  && <0.3
diff --git a/src/Protolude/Base.hs b/src/Protolude/Base.hs
index 4de2c9836..0682d1eb8 100644
--- a/src/Protolude/Base.hs
+++ b/src/Protolude/Base.hs
@@ -67,7 +67,7 @@ import GHC.Real as Base (
   , fromIntegral
   , fromRational
   , gcd
-#if MIN_VERSION_base(4,9,0)
+#if MIN_VERSION_base(4,9,0) && !MIN_VERSION_base(4,15,0)
 #if defined(MIN_VERSION_integer_gmp)
   , gcdInt'
   , gcdWord'