diff --git a/src/GUE.bb b/src/GUE.bb
index 6d1e1269..393fc6a6 100644
--- a/src/GUE.bb
+++ b/src/GUE.bb
@@ -10,6 +10,7 @@ ChangeDir RootDir$
 
 Include "Modules\RCEnet.bb"
 Include "Modules\Media.bb"
+Include "Modules\MediaImport.bb"
 Include "Modules\MediaDialogs.bb"
 Include "Modules\Projectiles.bb"
 Include "Modules\Language.bb"
@@ -6288,29 +6289,18 @@ Cls
 						If (Flags And 1) <> False Then IsAnim = True Else IsAnim = False
 						IsEncrypted = False
 
-						; Remove trailing slash
-						If Right$(App\CurrentFile$, 1) = "\"
-							App\CurrentFile$ = Left$(App\CurrentFile$, Len(App\CurrentFile$) - 1)
-						EndIf
+						App\CurrentFile$ = MediaImportTrimTrailingSlash$(App\CurrentFile$)
+						Filename$ = MediaImportRelativePath$(App\CurrentFile$, "Data\Meshes\", CurrentDir$(), MediaFolder$)
 
 						; Copy file/folder if required
-						If Instr(App\CurrentFile$, "Data\Meshes\") = 0 ;TODO: If RootDir is changed this may break
-							Filename$ = App\CurrentFile$
-							If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-							For i = Len(App\CurrentFile$) To 1 Step -1
-								If Mid$(App\CurrentFile$, i, 1) = "\" Or Mid$(App\CurrentFile$, i, 1) = "/"
-									Filename$ = Mid$(App\CurrentFile$, i + 1)
-									If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-									Exit
-								EndIf
-							Next
-							If FileType(App\CurrentFile$) = 1
-								CopyFile(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Meshes\" + Filename$)
-							ElseIf FileType(App\CurrentFile$) = 2
-								CopyTree(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Meshes\" + Filename$)
+						If MediaImportShouldCopy(App\CurrentFile$, "Data\Meshes\", CurrentDir$())
+							Local sourcePath$ = MediaImportSourcePath$(App\CurrentFile$, CurrentDir$())
+							Local destinationPath$ = MediaImportSourcePath$("Data\Meshes\" + Filename$, CurrentDir$())
+							If FileType(sourcePath$) = 1
+								CopyFile(sourcePath$, destinationPath$)
+							ElseIf FileType(sourcePath$) = 2
+								CopyTree(sourcePath$, destinationPath$)
 							EndIf
-						Else
-							Filename$ = Right$(App\CurrentFile$, Len(App\CurrentFile$) - Len("Data\Meshes\")) ;TODO: If RootDir is changed this may break
 						EndIf
 
 						; Single file
@@ -6333,29 +6323,18 @@ Cls
 						; Get extra options
 						Flags = TextureDialog()
 
-						; Remove trailing slash
-						If Right$(App\CurrentFile$, 1) = "\"
-							App\CurrentFile$ = Left$(App\CurrentFile$, Len(App\CurrentFile$) - 1)
-						EndIf
+						App\CurrentFile$ = MediaImportTrimTrailingSlash$(App\CurrentFile$)
+						Filename$ = MediaImportRelativePath$(App\CurrentFile$, "Data\Textures\", CurrentDir$(), MediaFolder$)
 
 						; Copy file/folder if required
-						If Instr(App\CurrentFile$, "Data\Textures\") = 0 ;TODO: If RootDir is changed this may break
-							Filename$ = App\CurrentFile$
-							If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-							For i = Len(App\CurrentFile$) To 1 Step -1
-								If Mid$(App\CurrentFile$, i, 1) = "\" Or Mid$(App\CurrentFile$, i, 1) = "/"
-									Filename$ = Mid$(App\CurrentFile$, i + 1)
-									If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-									Exit
-								EndIf
-							Next
-							If FileType(App\CurrentFile$) = 1
-								CopyFile(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Textures\" + Filename$)
-							ElseIf FileType(App\CurrentFile$) = 2
-								CopyTree(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Textures\" + Filename$)
+						If MediaImportShouldCopy(App\CurrentFile$, "Data\Textures\", CurrentDir$())
+							Local sourcePath$ = MediaImportSourcePath$(App\CurrentFile$, CurrentDir$())
+							Local destinationPath$ = MediaImportSourcePath$("Data\Textures\" + Filename$, CurrentDir$())
+							If FileType(sourcePath$) = 1
+								CopyFile(sourcePath$, destinationPath$)
+							ElseIf FileType(sourcePath$) = 2
+								CopyTree(sourcePath$, destinationPath$)
 							EndIf
-						Else
-							Filename$ = Right$(App\CurrentFile$, Len(App\CurrentFile$) - Len("Data\Textures\")) ;TODO: If RootDir is changed this may break
 						EndIf
 
 						; Single file
@@ -6379,29 +6358,18 @@ Cls
 						; Get extra options
 						Is3D = SoundDialog()
 
-						; Remove trailing slash
-						If Right$(App\CurrentFile$, 1) = "\"
-							App\CurrentFile$ = Left$(App\CurrentFile$, Len(App\CurrentFile$) - 1)
-						EndIf
+						App\CurrentFile$ = MediaImportTrimTrailingSlash$(App\CurrentFile$)
+						Filename$ = MediaImportRelativePath$(App\CurrentFile$, "Data\Sounds\", CurrentDir$(), MediaFolder$)
 
 						; Copy file/folder if required
-						If Instr(App\CurrentFile$, "Data\Sounds\") = 0 ;TODO: If RootDir is changed this may break
-							Filename$ = App\CurrentFile$
-							If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-							For i = Len(App\CurrentFile$) To 1 Step -1
-								If Mid$(App\CurrentFile$, i, 1) = "\" Or Mid$(App\CurrentFile$, i, 1) = "/"
-									Filename$ = Mid$(App\CurrentFile$, i + 1)
-									If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-									Exit
-								EndIf
-							Next
-							If FileType(App\CurrentFile$) = 1
-								CopyFile(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Sounds\" + Filename$)
-							ElseIf FileType(App\CurrentFile$) = 2
-								CopyTree(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Sounds\" + Filename$)
+						If MediaImportShouldCopy(App\CurrentFile$, "Data\Sounds\", CurrentDir$())
+							Local sourcePath$ = MediaImportSourcePath$(App\CurrentFile$, CurrentDir$())
+							Local destinationPath$ = MediaImportSourcePath$("Data\Sounds\" + Filename$, CurrentDir$())
+							If FileType(sourcePath$) = 1
+								CopyFile(sourcePath$, destinationPath$)
+							ElseIf FileType(sourcePath$) = 2
+								CopyTree(sourcePath$, destinationPath$)
 							EndIf
-						Else
-							Filename$ = Right$(App\CurrentFile$, Len(App\CurrentFile$) - Len("Data\Sounds\")) ;TODO: If RootDir is changed this may break
 						EndIf
 
 						; Single file
@@ -6424,29 +6392,18 @@ Cls
 					Result = FUI_CustomOpenDialog("Choose file to add...", "Data\Music\", FileTypes$, False, True)
 					If Result = True
 
-						; Remove trailing slash
-						If Right$(App\CurrentFile$, 1) = "\"
-							App\CurrentFile$ = Left$(App\CurrentFile$, Len(App\CurrentFile$) - 1)
-						EndIf
+						App\CurrentFile$ = MediaImportTrimTrailingSlash$(App\CurrentFile$)
+						Filename$ = MediaImportRelativePath$(App\CurrentFile$, "Data\Music\", CurrentDir$(), MediaFolder$)
 
 						; Copy file/folder if required
-						If Instr(App\CurrentFile$, "Data\Music\") = 0 ;TODO: If RootDir is changed this may break
-							Filename$ = App\CurrentFile$
-							If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-							For i = Len(App\CurrentFile$) To 1 Step -1
-								If Mid$(App\CurrentFile$, i, 1) = "\" Or Mid$(App\CurrentFile$, i, 1) = "/"
-									Filename$ = Mid$(App\CurrentFile$, i + 1)
-									If MediaFolder$ <> "" Then Filename$ = MediaFolder$ + "\" + Filename$
-									Exit
-								EndIf
-							Next
-							If FileType(App\CurrentFile$) = 1
-								CopyFile(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Music\" + Filename$)
-							ElseIf FileType(App\CurrentFile$) = 2
-								CopyTree(CurrentDir$() + App\CurrentFile$, CurrentDir$() + "Data\Music\" + Filename$)
+						If MediaImportShouldCopy(App\CurrentFile$, "Data\Music\", CurrentDir$())
+							Local sourcePath$ = MediaImportSourcePath$(App\CurrentFile$, CurrentDir$())
+							Local destinationPath$ = MediaImportSourcePath$("Data\Music\" + Filename$, CurrentDir$())
+							If FileType(sourcePath$) = 1
+								CopyFile(sourcePath$, destinationPath$)
+							ElseIf FileType(sourcePath$) = 2
+								CopyTree(sourcePath$, destinationPath$)
 							EndIf
-						Else
-							Filename$ = Right$(App\CurrentFile$, Len(App\CurrentFile$) - Len("Data\Music\")) ;TODO: If RootDir is changed this may break
 						EndIf
 
 						; Single file
@@ -10692,4 +10649,4 @@ Function menuSaveAll()
 				; Save interface
 				SaveInterfaceSettings("Data\Game Data\Interface.dat")
 				InterfaceSaved = True
-End Function
\ No newline at end of file
+End Function
diff --git a/src/Modules/MediaImport.bb b/src/Modules/MediaImport.bb
new file mode 100644
index 00000000..bb0b2f13
--- /dev/null
+++ b/src/Modules/MediaImport.bb
@@ -0,0 +1,82 @@
+Strict
+
+Function MediaImportNormalizeSlashes$(path$)
+	Local normalized$ = ""
+	For i = 1 To Len(path$)
+		Local ch$ = Mid$(path$, i, 1)
+		If ch$ = "/" Then ch$ = "\"
+		normalized$ = normalized$ + ch$
+	Next
+	Return normalized$
+End Function
+
+Function MediaImportTrimTrailingSlash$(path$)
+	path$ = MediaImportNormalizeSlashes$(path$)
+	While Len(path$) > 0
+		Local ch$ = Mid$(path$, Len(path$), 1)
+		If ch$ <> "\" Then Exit
+		path$ = Left$(path$, Len(path$) - 1)
+	Wend
+	Return path$
+End Function
+
+Function MediaImportEnsureTrailingSlash$(path$)
+	path$ = MediaImportNormalizeSlashes$(path$)
+	If Right$(path$, 1) <> "\" Then path$ = path$ + "\"
+	Return path$
+End Function
+
+Function MediaImportIsAbsolute%(path$)
+	path$ = MediaImportNormalizeSlashes$(path$)
+	If Len(path$) >= 2 And Mid$(path$, 2, 1) = ":" Then Return True
+	If Left$(path$, 2) = "\\" Then Return True
+	Return False
+End Function
+
+Function MediaImportHasPrefix%(path$, prefix$)
+	If Len(path$) < Len(prefix$) Then Return False
+	Return Lower$(Left$(path$, Len(prefix$))) = Lower$(prefix$)
+End Function
+
+Function MediaImportFileName$(path$)
+	path$ = MediaImportTrimTrailingSlash$(path$)
+	For i = Len(path$) To 1 Step -1
+		Local ch$ = Mid$(path$, i, 1)
+		If ch$ = "\" Or ch$ = "/" Then Return Mid$(path$, i + 1)
+	Next
+	Return path$
+End Function
+
+Function MediaImportSourcePath$(path$, currentDir$)
+	path$ = MediaImportTrimTrailingSlash$(path$)
+	If MediaImportIsAbsolute(path$) Then Return path$
+	Return MediaImportEnsureTrailingSlash$(currentDir$) + path$
+End Function
+
+Function MediaImportShouldCopy%(path$, mediaRoot$, currentDir$)
+	path$ = MediaImportTrimTrailingSlash$(path$)
+	Local relativeRoot$ = MediaImportEnsureTrailingSlash$(mediaRoot$)
+	Local absoluteRoot$ = MediaImportSourcePath$(relativeRoot$, currentDir$)
+	If MediaImportHasPrefix(path$, relativeRoot$) Then Return False
+	If MediaImportHasPrefix(path$, absoluteRoot$) Then Return False
+	Return True
+End Function
+
+Function MediaImportRelativePath$(path$, mediaRoot$, currentDir$, mediaFolder$ = "")
+	path$ = MediaImportTrimTrailingSlash$(path$)
+	Local relativeRoot$ = MediaImportEnsureTrailingSlash$(mediaRoot$)
+	Local absoluteRoot$ = MediaImportSourcePath$(relativeRoot$, currentDir$)
+
+	If MediaImportHasPrefix(path$, relativeRoot$)
+		Return Mid$(path$, Len(relativeRoot$) + 1)
+	EndIf
+
+	If MediaImportHasPrefix(path$, absoluteRoot$)
+		Return Mid$(path$, Len(absoluteRoot$) + 1)
+	EndIf
+
+	Local filename$ = MediaImportFileName$(path$)
+	Local folder$ = MediaImportTrimTrailingSlash$(mediaFolder$)
+	If folder$ <> "" Then filename$ = folder$ + "\" + filename$
+	Return filename$
+End Function
diff --git a/src/Tests/Modules/MediaImportTest.bb b/src/Tests/Modules/MediaImportTest.bb
new file mode 100644
index 00000000..8073f979
--- /dev/null
+++ b/src/Tests/Modules/MediaImportTest.bb
@@ -0,0 +1,25 @@
+Strict
+EnableGC
+
+Include "Modules\MediaImport.bb"
+
+Test testMediaImportTreatsProjectRelativeSelectionAsExistingMedia()
+	Assert(MediaImportShouldCopy("Data\Textures\GUI\Button.png", "Data\Textures\", "C:\RCCE") = False)
+	Assert(MediaImportRelativePath$("Data\Textures\GUI\Button.png", "Data\Textures\", "C:\RCCE") = "GUI\Button.png")
+End Test
+
+Test testMediaImportTreatsAbsoluteProjectSelectionAsExistingMedia()
+	Assert(MediaImportShouldCopy("C:/RCCE/Data/Textures/GUI/Button.png", "Data\Textures\", "C:\RCCE") = False)
+	Assert(MediaImportRelativePath$("C:/RCCE/Data/Textures/GUI/Button.png", "Data\Textures\", "C:\RCCE") = "GUI\Button.png")
+End Test
+
+Test testMediaImportKeepsAbsoluteSourcePathsForExternalSelections()
+	Assert(MediaImportShouldCopy("D:/Downloads/Button.png", "Data\Textures\", "C:\RCCE") = True)
+	Assert(MediaImportSourcePath$("D:/Downloads/Button.png", "C:\RCCE") = "D:\Downloads\Button.png")
+	Assert(MediaImportRelativePath$("D:/Downloads/Button.png", "Data\Textures\", "C:\RCCE", "GUI") = "GUI\Button.png")
+End Test
+
+Test testMediaImportUsesFolderNameForExternalFolderSelections()
+	Assert(MediaImportRelativePath$("D:\Downloads\Creatures\", "Data\Meshes\", "C:\RCCE") = "Creatures")
+	Assert(MediaImportSourcePath$("Data\Meshes\Creatures\", "C:\RCCE") = "C:\RCCE\Data\Meshes\Creatures")
+End Test