diff --git a/crytic_compile/platform/etherscan.py b/crytic_compile/platform/etherscan.py
index 7ba17efe..5483c921 100644
--- a/crytic_compile/platform/etherscan.py
+++ b/crytic_compile/platform/etherscan.py
@@ -362,8 +362,8 @@ def compile(self, crytic_compile: "CryticCompile", **kwargs: str) -> None:
         if "Proxy" in result and result["Proxy"] == "1":
             assert "Implementation" in result
             implementation = str(result["Implementation"])
-            if prefix is not None:
-                implementation = f"{prefix}:{implementation}"
+            if target.startswith(tuple(SUPPORTED_NETWORK)):
+                implementation = f"{target[:target.find(':')]}:{implementation}"
             compilation_unit.implementation_address = implementation
 
         solc_standard_json.standalone_compile(filenames, compilation_unit, working_dir=working_dir)