diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 5d38e0c2b..b1b47c45f 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -121,7 +121,7 @@ struct GitInputScheme : InputScheme
             args.push_back(*ref);
         }
 
-        if (input.getRev()) throw Error("cloning a specific revision is not implemented");
+        if (input.getRev()) throw UnimplementedError("cloning a specific revision is not implemented");
 
         args.push_back(destDir);
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index b59bfa8bc..73e29390d 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1197,7 +1197,7 @@ void DerivationGoal::haveDerivation()
 
     if (parsedDrv->contentAddressed()) {
         settings.requireExperimentalFeature("ca-derivations");
-        throw Error("ca-derivations isn't implemented yet");
+        throw UnimplementedError("ca-derivations isn't implemented yet");
     }
 
 
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index b8e2494a3..04cf14cba 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -45,7 +45,7 @@ struct DerivationOutput
     /* DEPRECATED: Remove after CA drvs are fully implemented */
     StorePath path(const Store & store, std::string_view drvName) const {
         auto p = pathOpt(store, drvName);
-        if (!p) throw Error("floating content-addressed derivations are not yet implemented");
+        if (!p) throw UnimplementedError("floating content-addressed derivations are not yet implemented");
         return *p;
     }
 };
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index 0daaf3be2..f3babcbde 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -192,6 +192,7 @@ public:
 
 MakeError(Error, BaseError);
 MakeError(UsageError, Error);
+MakeError(UnimplementedError, Error);
 
 class SysError : public Error
 {