diff --git a/stdlib/LibGit2/src/repository.jl b/stdlib/LibGit2/src/repository.jl
index 8cf9cac3439f3..57375703ad1ae 100644
--- a/stdlib/LibGit2/src/repository.jl
+++ b/stdlib/LibGit2/src/repository.jl
@@ -91,6 +91,7 @@ in the `.git` subdirectory. This means that there is nowhere to check out the wo
 tree, and no tracking information for remote branches or configurations is present.
 """
 function isbare(repo::GitRepo)
+    @assert repo.ptr != C_NULL
     return ccall((:git_repository_is_bare, :libgit2), Cint, (Ptr{Cvoid},), repo.ptr) == 1
 end
 
@@ -101,6 +102,7 @@ Determine if `repo` is detached - that is, whether its HEAD points to a commit
 (detached) or whether HEAD points to a branch tip (attached).
 """
 function isattached(repo::GitRepo)
+    @assert repo.ptr != C_NULL
     ccall((:git_repository_head_detached, :libgit2), Cint, (Ptr{Cvoid},), repo.ptr) != 1
 end
 
@@ -129,6 +131,7 @@ end
 
 function (::Type{T})(repo::GitRepo, spec::AbstractString) where T<:GitObject
     obj_ptr_ptr = Ref{Ptr{Cvoid}}(C_NULL)
+    @assert repo.ptr != C_NULL
     @check ccall((:git_revparse_single, :libgit2), Cint,
                  (Ptr{Ptr{Cvoid}}, Ptr{Cvoid}, Cstring), obj_ptr_ptr, repo.ptr, spec)
     # check object is of correct type
@@ -143,6 +146,7 @@ function (::Type{T})(repo::GitRepo, oid::GitHash) where T<:GitObject
     oid_ptr  = Ref(oid)
     obj_ptr_ptr = Ref{Ptr{Cvoid}}(C_NULL)
 
+    @assert repo.ptr != C_NULL
     @check ccall((:git_object_lookup, :libgit2), Cint,
                  (Ptr{Ptr{Cvoid}}, Ptr{Cvoid}, Ptr{GitHash}, Consts.OBJECT),
                  obj_ptr_ptr, repo.ptr, oid_ptr, Consts.OBJECT(T))
@@ -153,6 +157,7 @@ function (::Type{T})(repo::GitRepo, oid::GitShortHash) where T<:GitObject
     oid_ptr  = Ref(oid.hash)
     obj_ptr_ptr = Ref{Ptr{Cvoid}}(C_NULL)
 
+    @assert repo.ptr != C_NULL
     @check ccall((:git_object_lookup_prefix, :libgit2), Cint,
                  (Ptr{Ptr{Cvoid}}, Ptr{Cvoid}, Ptr{GitHash}, Csize_t, Consts.OBJECT),
                  obj_ptr_ptr, repo.ptr, oid_ptr, oid.len, Consts.OBJECT(T))
@@ -174,6 +179,7 @@ Return the location of the "git" files of `repo`:
 See also [`workdir`](@ref), [`path`](@ref).
 """
 function gitdir(repo::GitRepo)
+    @assert repo.ptr != C_NULL
     return unsafe_string(ccall((:git_repository_path, :libgit2), Cstring,
                         (Ptr{Cvoid},), repo.ptr))
 end
@@ -193,6 +199,7 @@ This will throw an error for bare repositories.
 See also [`gitdir`](@ref), [`path`](@ref).
 """
 function workdir(repo::GitRepo)
+    @assert repo.ptr != C_NULL
     sptr = ccall((:git_repository_workdir, :libgit2), Cstring,
                 (Ptr{Cvoid},), repo.ptr)
     sptr == C_NULL && throw(GitError(Error.Object, Error.ERROR, "No working directory found."))
@@ -290,6 +297,7 @@ information.
 """
 function GitDescribeResult(repo::GitRepo; options::DescribeOptions=DescribeOptions())
     result_ptr_ptr = Ref{Ptr{Cvoid}}(C_NULL)
+    @assert repo.ptr != C_NULL
     @check ccall((:git_describe_workdir, :libgit2), Cint,
                  (Ptr{Ptr{Cvoid}}, Ptr{Cvoid}, Ptr{DescribeOptions}),
                  result_ptr_ptr, repo.ptr, Ref(options))
@@ -330,6 +338,7 @@ be performed. See [`CheckoutOptions`](@ref) for more information.
 """
 function checkout_tree(repo::GitRepo, obj::GitObject;
                        options::CheckoutOptions = CheckoutOptions())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_checkout_tree, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Ptr{CheckoutOptions}),
                  repo.ptr, obj.ptr, Ref(options))
@@ -344,6 +353,7 @@ See [`CheckoutOptions`](@ref) for more information.
 """
 function checkout_index(repo::GitRepo, idx::Union{GitIndex, Nothing} = nothing;
                         options::CheckoutOptions = CheckoutOptions())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_checkout_index, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Ptr{CheckoutOptions}),
                  repo.ptr,
@@ -362,6 +372,7 @@ Update the index and working tree of `repo` to match the commit pointed to by HE
     conflicts.
 """
 function checkout_head(repo::GitRepo; options::CheckoutOptions = CheckoutOptions())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_checkout_head, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{CheckoutOptions}),
                  repo.ptr, Ref(options))
@@ -379,6 +390,7 @@ The keyword argument `options` sets checkout and merge options for the cherrypic
     call [`commit`](@ref) yourself.
 """
 function cherrypick(repo::GitRepo, commit::GitCommit; options::CherrypickOptions = CherrypickOptions())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_cherrypick, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Ptr{CherrypickOptions}),
                  repo.ptr, commit.ptr, Ref(options))
@@ -386,6 +398,7 @@ end
 
 """Updates some entries, determined by the `pathspecs`, in the index from the target commit tree."""
 function reset!(repo::GitRepo, obj::Union{GitObject, Nothing}, pathspecs::AbstractString...)
+    @assert repo.ptr != C_NULL
     @check ccall((:git_reset_default, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Ptr{StrArrayStruct}),
                  repo.ptr,
@@ -397,6 +410,7 @@ end
 """Sets the current head to the specified commit oid and optionally resets the index and working tree to match."""
 function reset!(repo::GitRepo, obj::GitObject, mode::Cint;
                checkout_opts::CheckoutOptions = CheckoutOptions())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_reset, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Cint, Ptr{CheckoutOptions}),
                   repo.ptr, obj.ptr, mode, Ref(checkout_opts))
@@ -452,6 +466,7 @@ false
 function fetchheads(repo::GitRepo)
     fh = FetchHead[]
     ffcb = fetchhead_foreach_cb()
+    @assert repo.ptr != C_NULL
     @check ccall((:git_repository_fetchhead_foreach, :libgit2), Cint,
                  (Ptr{Cvoid}, Ptr{Cvoid}, Any),
                  repo.ptr, ffcb, fh)
@@ -465,6 +480,7 @@ Return a vector of the names of the remotes of `repo`.
 """
 function remotes(repo::GitRepo)
     sa_ref = Ref(StrArrayStruct())
+    @assert repo.ptr != C_NULL
     @check ccall((:git_remote_list, :libgit2), Cint,
                   (Ptr{StrArrayStruct}, Ptr{Cvoid}), sa_ref, repo.ptr)
     res = convert(Vector{String}, sa_ref[])
@@ -474,6 +490,10 @@ end
 
 function Base.show(io::IO, repo::GitRepo)
     print(io, "LibGit2.GitRepo(")
-    show(io, path(repo))
+    if repo.ptr == C_NULL
+        print(io, "<closed>")
+    else
+        show(io, path(repo))
+    end
     print(io, ")")
 end
diff --git a/stdlib/LibGit2/test/libgit2.jl b/stdlib/LibGit2/test/libgit2.jl
index f0990216f9515..17ec68cfdcf3d 100644
--- a/stdlib/LibGit2/test/libgit2.jl
+++ b/stdlib/LibGit2/test/libgit2.jl
@@ -1274,6 +1274,13 @@ mktempdir() do dir
         end
     end
 
+    @testset "Show closed repo" begin
+        # Make sure this doesn't crash
+        buf = IOBuffer()
+        Base.show(buf, LibGit2.with(identity, LibGit2.GitRepo(test_repo)))
+        @test String(take!(buf)) == "LibGit2.GitRepo(<closed>)"
+    end
+
     @testset "Fetch from cache repository" begin
         LibGit2.with(LibGit2.GitRepo(test_repo)) do repo
             # fetch changes