diff --git a/src/Operations.jl b/src/Operations.jl
index 7c65782242..5e4b12c595 100644
--- a/src/Operations.jl
+++ b/src/Operations.jl
@@ -225,13 +225,14 @@ end
 # This has to be done after the packages have been downloaded
 # since we need access to the Project file to read the information
 # about extensions
-function fixup_ext!(env::EnvCache)
+function fixups_from_projectfile!(env::EnvCache)
     for pkg in values(env.manifest)
         v = joinpath(source_path(env.manifest_file, pkg), "Project.toml")
         if isfile(v)
             p = Types.read_project(v)
             pkg.weakdeps = p.weakdeps
             pkg.exts = p.exts
+            pkg.entryfile = p.entryfile
             for (name, _) in p.weakdeps
                 if !haskey(p.deps, name)
                     delete!(pkg.deps, name)
@@ -1506,7 +1507,7 @@ function add(ctx::Context, pkgs::Vector{PackageSpec}, new_git=Set{UUID}();
         man_pkgs, deps_map = _resolve(ctx.io, ctx.env, ctx.registries, pkgs, preserve, ctx.julia_version)
         update_manifest!(ctx.env, man_pkgs, deps_map, ctx.julia_version)
         new_apply = download_source(ctx)
-        fixup_ext!(ctx.env)
+        fixups_from_projectfile!(ctx.env)
 
         # After downloading resolutionary packages, search for (Julia)Artifacts.toml files
         # and ensure they are all downloaded and unpacked as well:
@@ -1550,7 +1551,7 @@ function develop(ctx::Context, pkgs::Vector{PackageSpec}, new_git::Set{UUID};
     pkgs, deps_map = _resolve(ctx.io, ctx.env, ctx.registries, pkgs, preserve, ctx.julia_version)
     update_manifest!(ctx.env, pkgs, deps_map, ctx.julia_version)
     new_apply = download_source(ctx)
-    fixup_ext!(ctx.env)
+    fixups_from_projectfile!(ctx.env)
     download_artifacts(ctx.env; platform=platform, julia_version=ctx.julia_version, io=ctx.io)
     write_env(ctx.env) # write env before building
     show_update(ctx.env, ctx.registries; io=ctx.io)
@@ -1691,7 +1692,7 @@ function up(ctx::Context, pkgs::Vector{PackageSpec}, level::UpgradeLevel;
     end
     update_manifest!(ctx.env, pkgs, deps_map, ctx.julia_version)
     new_apply = download_source(ctx)
-    fixup_ext!(ctx.env)
+    fixups_from_projectfile!(ctx.env)
     download_artifacts(ctx.env, julia_version=ctx.julia_version, io=ctx.io)
     write_env(ctx.env; skip_writing_project) # write env before building
     show_update(ctx.env, ctx.registries; io=ctx.io, hidden_upgrades_info = true)
@@ -1737,7 +1738,7 @@ function pin(ctx::Context, pkgs::Vector{PackageSpec})
 
     update_manifest!(ctx.env, pkgs, deps_map, ctx.julia_version)
     new = download_source(ctx)
-    fixup_ext!(ctx.env)
+    fixups_from_projectfile!(ctx.env)
     download_artifacts(ctx.env; julia_version=ctx.julia_version, io=ctx.io)
     write_env(ctx.env) # write env before building
     show_update(ctx.env, ctx.registries; io=ctx.io)
@@ -1785,7 +1786,7 @@ function free(ctx::Context, pkgs::Vector{PackageSpec}; err_if_free=true)
 
         update_manifest!(ctx.env, pkgs, deps_map, ctx.julia_version)
         new = download_source(ctx)
-        fixup_ext!(ctx.env)
+        fixups_from_projectfile!(ctx.env)
         download_artifacts(ctx.env, io=ctx.io)
         write_env(ctx.env) # write env before building
         show_update(ctx.env, ctx.registries; io=ctx.io)
diff --git a/src/Types.jl b/src/Types.jl
index d319edd0d5..6fac4b8465 100644
--- a/src/Types.jl
+++ b/src/Types.jl
@@ -234,7 +234,7 @@ Base.@kwdef mutable struct Project
     uuid::Union{UUID, Nothing} = nothing
     version::Union{VersionTypes, Nothing} = nothing
     manifest::Union{String, Nothing} = nothing
-    path::Union{String, Nothing} = nothing
+    entryfile::Union{String, Nothing} = nothing
     # Sections
     deps::Dict{String,UUID} = Dict{String,UUID}()
     # deps that are also in weakdeps for backwards compat
@@ -258,6 +258,7 @@ Base.@kwdef mutable struct PackageEntry
     name::Union{String,Nothing} = nothing
     version::Union{VersionNumber,Nothing} = nothing
     path::Union{String,Nothing} = nothing
+    entryfile::Union{String,Nothing} = nothing
     pinned::Bool = false
     repo::GitRepo = GitRepo()
     tree_hash::Union{Nothing,SHA1} = nothing
@@ -270,6 +271,7 @@ end
 Base.:(==)(t1::PackageEntry, t2::PackageEntry) = t1.name == t2.name &&
     t1.version == t2.version &&
     t1.path == t2.path &&
+    t1.entryfile == t2.entryfile &&
     t1.pinned == t2.pinned &&
     t1.repo == t2.repo &&
     t1.tree_hash == t2.tree_hash &&
@@ -278,7 +280,7 @@ Base.:(==)(t1::PackageEntry, t2::PackageEntry) = t1.name == t2.name &&
     t1.exts == t2.exts &&
     t1.uuid == t2.uuid
     # omits `other`
-Base.hash(x::PackageEntry, h::UInt) = foldr(hash, [x.name, x.version, x.path, x.pinned, x.repo, x.tree_hash, x.deps, x.weakdeps, x.exts, x.uuid], init=h)  # omits `other`
+Base.hash(x::PackageEntry, h::UInt) = foldr(hash, [x.name, x.version, x.path, x.entryfile, x.pinned, x.repo, x.tree_hash, x.deps, x.weakdeps, x.exts, x.uuid], init=h)  # omits `other`
 
 Base.@kwdef mutable struct Manifest
     julia_version::Union{Nothing,VersionNumber} = nothing # only set to VERSION when resolving
@@ -629,9 +631,10 @@ function read_package(path::String)
         pkgerror("expected a `uuid` entry in project file at `$(abspath(path))`")
     end
     name = project.name
-    pkgpath = joinpath(dirname(path), something(project.path, ""))
-    if !isfile(joinpath(pkgpath, "src", "$name.jl"))
-        pkgerror("expected the file `src/$name.jl` to exist for package `$name` at `$(dirname(path))`")
+    entry_point = something(project.entryfile, joinpath("src", "$(name).jl"))
+    pkgpath = joinpath(dirname(path), entry_point)
+    if !isfile(pkgpath)
+        pkgerror("expected the file `$pkgpath` to exist for package `$name` at `$(dirname(path))`")
     end
     return project
 end
diff --git a/src/manifest.jl b/src/manifest.jl
index 074bb73fbb..627f7e92fc 100644
--- a/src/manifest.jl
+++ b/src/manifest.jl
@@ -279,6 +279,7 @@ function destructure(manifest::Manifest)::Dict
             path = join(splitpath(path), "/")
         end
         entry!(new_entry, "path", path)
+        entry!(new_entry, "entryfile", entry.entryfile)
         repo_source = entry.repo.source
         if repo_source !== nothing && Sys.iswindows() && !isabspath(repo_source) && !isurl(repo_source)
             repo_source = join(splitpath(repo_source), "/")
diff --git a/src/project.jl b/src/project.jl
index 1139089a98..f7a7e83757 100644
--- a/src/project.jl
+++ b/src/project.jl
@@ -182,7 +182,10 @@ function Project(raw::Dict; file=nothing)
     project.other    = raw
     project.name     = get(raw, "name", nothing)::Union{String, Nothing}
     project.manifest = get(raw, "manifest", nothing)::Union{String, Nothing}
-    project.path     = get(raw, "path", nothing)::Union{String, Nothing}
+    project.entryfile     = get(raw, "path", nothing)::Union{String, Nothing}
+    if project.entryfile === nothing
+        project.entryfile = get(raw, "entryfile", nothing)::Union{String, Nothing}
+    end
     project.uuid     = read_project_uuid(get(raw, "uuid", nothing))
     project.version  = read_project_version(get(raw, "version", nothing))
     project.deps     = read_project_deps(get(raw, "deps", nothing), "deps")
@@ -243,7 +246,7 @@ function destructure(project::Project)::Dict
     entry!("version",  project.version)
     entry!("workspace", project.workspace)
     entry!("manifest", project.manifest)
-    entry!("path",     project.path)
+    entry!("entryfile",     project.entryfile)
     entry!("deps",     merge(project.deps, project._deps_weak))
     entry!("weakdeps", project.weakdeps)
     entry!("sources",  project.sources)
diff --git a/test/new.jl b/test/new.jl
index 6ab8e6a6d7..1561840b34 100644
--- a/test/new.jl
+++ b/test/new.jl
@@ -3198,4 +3198,20 @@ if :version in fieldnames(Base.PkgOrigin)
 end
 end
 
+temp_pkg_dir() do project_path
+    @testset "test entryfile entries" begin
+        mktempdir() do dir
+            path = abspath(joinpath(dirname(pathof(Pkg)), "../test", "test_packages", "ProjectPath"))
+            cp(path, joinpath(dir, "ProjectPath"))
+            cd(joinpath(dir, "ProjectPath")) do
+                with_current_env() do
+                    Pkg.resolve()
+                    @test success(run(`$(Base.julia_cmd()) --startup-file=no --project -e 'using ProjectPath'`))
+                    @test success(run(`$(Base.julia_cmd()) --startup-file=no --project -e 'using ProjectPathDep'`))
+                end
+            end
+        end
+    end
+end
+
 end #module
diff --git a/test/test_packages/ProjectPath/CustomPath.jl b/test/test_packages/ProjectPath/CustomPath.jl
new file mode 100644
index 0000000000..ecc39cc525
--- /dev/null
+++ b/test/test_packages/ProjectPath/CustomPath.jl
@@ -0,0 +1,7 @@
+module ProjectPath
+
+using ProjectPathDep
+
+greet() = print("Hello World!")
+
+end # module ProjectPath
diff --git a/test/test_packages/ProjectPath/Project.toml b/test/test_packages/ProjectPath/Project.toml
new file mode 100644
index 0000000000..c7735e2deb
--- /dev/null
+++ b/test/test_packages/ProjectPath/Project.toml
@@ -0,0 +1,10 @@
+name = "ProjectPath"
+uuid = "32833bde-7fc1-4d28-8365-9d01e1bcbc1b"
+entryfile = "CustomPath.jl"
+version = "0.1.0"
+
+[deps]
+ProjectPathDep = "f18633fc-8799-43ff-aa06-99ed830dc572"
+
+[sources]
+ProjectPathDep = {path = "ProjectPathDep"}
diff --git a/test/test_packages/ProjectPath/ProjectPathDep/CustomPath.jl b/test/test_packages/ProjectPath/ProjectPathDep/CustomPath.jl
new file mode 100644
index 0000000000..adbe508f0c
--- /dev/null
+++ b/test/test_packages/ProjectPath/ProjectPathDep/CustomPath.jl
@@ -0,0 +1,5 @@
+module ProjectPathDep
+
+greet() = print("Hello World!")
+
+end # module ProjectPathDep
diff --git a/test/test_packages/ProjectPath/ProjectPathDep/Project.toml b/test/test_packages/ProjectPath/ProjectPathDep/Project.toml
new file mode 100644
index 0000000000..c69e54e8c9
--- /dev/null
+++ b/test/test_packages/ProjectPath/ProjectPathDep/Project.toml
@@ -0,0 +1,4 @@
+name = "ProjectPathDep"
+uuid = "f18633fc-8799-43ff-aa06-99ed830dc572"
+version = "0.1.0"
+entryfile = "CustomPath.jl"