diff --git a/lib/spack/spack/detection/path.py b/lib/spack/spack/detection/path.py
index 96535e7e484..6d6026bee2b 100644
--- a/lib/spack/spack/detection/path.py
+++ b/lib/spack/spack/detection/path.py
@@ -18,6 +18,7 @@
 import llnl.util.lang
 import llnl.util.tty
 
+import spack.package_base
 import spack.util.elf as elf_utils
 import spack.util.environment
 import spack.util.environment as environment
@@ -200,7 +201,7 @@ class Finder:
     def default_path_hints(self) -> List[str]:
         return []
 
-    def search_patterns(self, *, pkg: Type["spack.package_base.PackageBase"]) -> List[str]:
+    def search_patterns(self, *, pkg: Type[spack.package_base.PackageBase]) -> List[str]:
         """Returns the list of patterns used to match candidate files.
 
         Args:
@@ -226,7 +227,7 @@ def prefix_from_path(self, *, path: str) -> str:
         raise NotImplementedError("must be implemented by derived classes")
 
     def detect_specs(
-        self, *, pkg: Type["spack.package_base.PackageBase"], paths: List[str]
+        self, *, pkg: Type[spack.package_base.PackageBase], paths: List[str]
     ) -> List[DetectedPackage]:
         """Given a list of files matching the search patterns, returns a list of detected specs.
 
@@ -327,7 +328,7 @@ class ExecutablesFinder(Finder):
     def default_path_hints(self) -> List[str]:
         return spack.util.environment.get_path("PATH")
 
-    def search_patterns(self, *, pkg: Type["spack.package_base.PackageBase"]) -> List[str]:
+    def search_patterns(self, *, pkg: Type[spack.package_base.PackageBase]) -> List[str]:
         result = []
         if hasattr(pkg, "executables") and hasattr(pkg, "platform_executables"):
             result = pkg.platform_executables()
@@ -353,7 +354,7 @@ class LibrariesFinder(Finder):
     DYLD_LIBRARY_PATH, DYLD_FALLBACK_LIBRARY_PATH, and standard system library paths
     """
 
-    def search_patterns(self, *, pkg: Type["spack.package_base.PackageBase"]) -> List[str]:
+    def search_patterns(self, *, pkg: Type[spack.package_base.PackageBase]) -> List[str]:
         result = []
         if hasattr(pkg, "libraries"):
             result = pkg.libraries