diff --git a/brownie/project/compiler/vyper.py b/brownie/project/compiler/vyper.py
index 9e2f3b59c..3163290b4 100644
--- a/brownie/project/compiler/vyper.py
+++ b/brownie/project/compiler/vyper.py
@@ -462,4 +462,4 @@ def _convert_to_semver(versions: List[PVersion]) -> List[Version]:
     vvm 0.2.0 switched to packaging.version but we are not ready to migrate brownie off of semantic-version.
     This function serves as a stopgap.
     """
-    return [Version(major=version.major, minor=version.minor, patch=version.micro, prerelease=''.join(str(x) for x in version.pre)) for version in versions]
\ No newline at end of file
+    return [Version(major=version.major, minor=version.minor, patch=version.micro, prerelease=''.join(str(x) for x in version.pre) if version.pre else None) for version in versions]
\ No newline at end of file