diff --git a/hls-tactics-plugin.cabal b/hls-tactics-plugin.cabal
--- a/hls-tactics-plugin.cabal
+++ b/hls-tactics-plugin.cabal
@@ -1,7 +1,7 @@
 cabal-version:      2.4
 category:           Development
 name:               hls-tactics-plugin
-version:            1.6.0.0
+version:            1.6.1.0
 synopsis:           Wingman plugin for Haskell Language Server
 description:
   Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
diff --git a/src/Wingman/KnownStrategies/QuickCheck.hs b/src/Wingman/KnownStrategies/QuickCheck.hs
--- a/src/Wingman/KnownStrategies/QuickCheck.hs
+++ b/src/Wingman/KnownStrategies/QuickCheck.hs
@@ -43,8 +43,9 @@
               mempty
               mempty
               mempty
-          $ noLoc $
-              let' [valBind (fromString "terminal") $ list $ fmap genExpr terminal] $
+          $ noLoc $ case terminal of
+            [onlyCon] -> genExpr onlyCon -- See #1879
+            _ -> let' [valBind (fromString "terminal") $ list $ fmap genExpr terminal] $
                 appDollar (mkFunc "sized") $ lambda [bvar' (mkVarOcc "n")] $
                   case' (infixCall "<=" (mkVal "n") (int 1))
                     [ match [conP (fromString "True") []] $
diff --git a/test/CodeAction/AutoSpec.hs b/test/CodeAction/AutoSpec.hs
--- a/test/CodeAction/AutoSpec.hs
+++ b/test/CodeAction/AutoSpec.hs
@@ -72,6 +72,7 @@
 
   describe "known" $ do
     autoTest 25 13 "GoldenArbitrary"
+    autoTest  6 13 "GoldenArbitrarySingleConstructor"
     autoTestNoWhitespace
               6 10 "KnownBigSemigroup"
     autoTest  4 10 "KnownThetaSemigroup"
diff --git a/test/golden/GoldenArbitrarySingleConstructor.expected.hs b/test/golden/GoldenArbitrarySingleConstructor.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/golden/GoldenArbitrarySingleConstructor.expected.hs
@@ -0,0 +1,7 @@
+data Gen a
+
+data Obj = Obj Int Bool Char String
+
+arbitrary :: Gen Obj
+arbitrary
+  = (((Obj <$> arbitrary) <*> arbitrary) <*> arbitrary) <*> arbitrary
diff --git a/test/golden/GoldenArbitrarySingleConstructor.hs b/test/golden/GoldenArbitrarySingleConstructor.hs
new file mode 100644
--- /dev/null
+++ b/test/golden/GoldenArbitrarySingleConstructor.hs
@@ -0,0 +1,6 @@
+data Gen a
+
+data Obj = Obj Int Bool Char String
+
+arbitrary :: Gen Obj
+arbitrary = _