diff --git a/Sources/XcodeGenKit/SourceGenerator.swift b/Sources/XcodeGenKit/SourceGenerator.swift
index 79a11ac7..ec7b18bd 100644
--- a/Sources/XcodeGenKit/SourceGenerator.swift
+++ b/Sources/XcodeGenKit/SourceGenerator.swift
@@ -422,8 +422,15 @@ class SourceGenerator {
             if !createIntermediateGroups {
                 rootGroups.insert(fileReference)
             }
+            
+            let buildPhase: BuildPhase?
+            if let targetBuildPhase = targetSource.buildPhase {
+                buildPhase = targetBuildPhase.buildPhase
+            } else {
+                buildPhase = .resources
+            }
 
-            let sourceFile = generateSourceFile(targetSource: targetSource, path: folderPath, buildPhase: targetSource.buildPhase?.buildPhase ?? .resources)
+            let sourceFile = generateSourceFile(targetSource: targetSource, path: folderPath, buildPhase: buildPhase)
 
             sourceFiles.append(sourceFile)
             sourceReference = fileReference