diff --git a/base/loading.jl b/base/loading.jl
index 057aa793aa5ed..43b2b7e23923b 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -11,7 +11,7 @@ elseif is_windows()
     # GetLongPathName Win32 function returns the case-preserved filename on NTFS.
     function isfile_casesensitive(path)
         isfile(path) || return false  # Fail fast
-        Filesystem.longpath(path) == path
+        basename(Filesystem.longpath(path)) == basename(path)
     end
 elseif is_apple()
     # HFS+ filesystem is case-preserving. The getattrlist API returns
diff --git a/test/loading.jl b/test/loading.jl
index f876b21def25a..c53d15532a212 100644
--- a/test/loading.jl
+++ b/test/loading.jl
@@ -15,18 +15,26 @@ thefname = "the fname!//\\&\1*"
 @test @__DIR__() == dirname(@__FILE__)
 
 # Issue #5789 and PR #13542:
-let true_filename = "cAsEtEsT.jl", lowered_filename="casetest.jl"
-    touch(true_filename)
-    @test Base.isfile_casesensitive(true_filename)
-    @test !Base.isfile_casesensitive(lowered_filename)
-    rm(true_filename)
-end
+cd(mktempdir()) do
+    let true_filename = "cAsEtEsT.jl", lowered_filename="casetest.jl"
+        touch(true_filename)
+        @test Base.isfile_casesensitive(true_filename)
+        @test !Base.isfile_casesensitive(lowered_filename)
+
+        # check that case-sensitivity only applies to basename of a path:
+        if isfile(lowered_filename) # case-insensitive filesystem
+            mkdir("cAsEtEsT")
+            touch(joinpath("cAsEtEsT", true_filename))
+            @test Base.isfile_casesensitive(joinpath("casetest", true_filename))
+            @test !Base.isfile_casesensitive(joinpath("casetest", lowered_filename))
+        end
+    end
 
-# Test Unicode normalization; pertinent for OS X
-let nfc_name = "\U00F4.jl"
-    touch(nfc_name)
-    @test Base.isfile_casesensitive(nfc_name)
-    rm(nfc_name)
+    # Test Unicode normalization; pertinent for OS X
+    let nfc_name = "\U00F4.jl"
+        touch(nfc_name)
+        @test Base.isfile_casesensitive(nfc_name)
+    end
 end
 
 let paddedname = "Ztest_sourcepath.jl"