diff --git a/python/src/com/jetbrains/python/psi/PyUtil.java b/python/src/com/jetbrains/python/psi/PyUtil.java
index 3c5c1b1ee3ce..3e368553c1fa 100644
--- a/python/src/com/jetbrains/python/psi/PyUtil.java
+++ b/python/src/com/jetbrains/python/psi/PyUtil.java
@@ -846,20 +846,19 @@ public class PyUtil {
     });
   }
 
-  public static <T, P> T getParameterizedCachedValue(@NotNull PsiElement element, @NotNull P param, @NotNull NotNullFunction<P, T> f) {
-    final Map<P, T> cache = CachedValuesManager.getCachedValue(element, new CachedValueProvider<Map<P, T>>() {
+  private static final Object NULL_VALUE = new Object();
+  public static <T, P> T getParameterizedCachedValue(@NotNull PsiElement element, @Nullable P param, @NotNull NullableFunction<P, T> f) {
+    final Map<P, Object> cache = CachedValuesManager.getCachedValue(element, new CachedValueProvider<Map<P, Object>>() {
       @Nullable
       @Override
-      public Result<Map<P, T>> compute() {
+      public Result<Map<P, Object>> compute() {
+        // TODO should be concurrent map instead
         return Result.create(Maps.newHashMap(), PsiModificationTracker.MODIFICATION_COUNT);
       }
     });
-    T result = cache.get(param);
-    if (result == null) {
-      result = f.fun(param);
-      cache.put(param, result);
-    }
-    return result;
+    final Object wrapped = cache.computeIfAbsent(param, p -> ObjectUtils.notNull(f.fun(param), NULL_VALUE));
+    //noinspection unchecked
+    return (T)ObjectUtils.nullizeByCondition(wrapped, NULL_VALUE::equals);
   }
 
   /**
diff --git a/python/src/com/jetbrains/python/psi/resolve/QualifiedNameFinder.java b/python/src/com/jetbrains/python/psi/resolve/QualifiedNameFinder.java
index bab8681fbbd6..1baebc144899 100644
--- a/python/src/com/jetbrains/python/psi/resolve/QualifiedNameFinder.java
+++ b/python/src/com/jetbrains/python/psi/resolve/QualifiedNameFinder.java
@@ -27,10 +27,7 @@ import com.intellij.psi.util.QualifiedName;
 import com.jetbrains.python.PyNames;
 import com.jetbrains.python.codeInsight.controlflow.ScopeOwner;
 import com.jetbrains.python.codeInsight.dataflow.scope.ScopeUtil;
-import com.jetbrains.python.psi.PyClass;
-import com.jetbrains.python.psi.PyElement;
-import com.jetbrains.python.psi.PyFile;
-import com.jetbrains.python.psi.PyFunction;
+import com.jetbrains.python.psi.*;
 import com.jetbrains.python.psi.impl.PyBuiltinCache;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -114,49 +111,51 @@ public class QualifiedNameFinder {
    */
   @Nullable
   public static QualifiedName findCanonicalImportPath(@NotNull PsiElement symbol, @Nullable PsiElement foothold) {
-    PsiFileSystemItem srcfile = symbol instanceof PsiFileSystemItem ? (PsiFileSystemItem)symbol : symbol.getContainingFile();
-    if (srcfile == null) {
-      return null;
-    }
-    VirtualFile virtualFile = srcfile.getVirtualFile();
-    if (virtualFile == null) {
-      return null;
-    }
-    if (srcfile instanceof PsiFile && symbol instanceof PsiNamedElement && !(symbol instanceof PsiFileSystemItem)) {
-      PsiElement toplevel = symbol;
-      if (symbol instanceof PyFunction) {
-        final PyClass containingClass = ((PyFunction)symbol).getContainingClass();
-        if (containingClass != null) {
-          toplevel = containingClass;
-        }
+    return PyUtil.getParameterizedCachedValue(symbol, foothold, param -> {
+      PsiFileSystemItem srcfile = symbol instanceof PsiFileSystemItem ? (PsiFileSystemItem)symbol : symbol.getContainingFile();
+      if (srcfile == null) {
+        return null;
       }
-      PsiDirectory dir = ((PsiFile)srcfile).getContainingDirectory();
-      while (dir != null) {
-        PsiFile initPy = dir.findFile(PyNames.INIT_DOT_PY);
-        if (initPy == null) {
-          break;
-        }
-        if (initPy instanceof PyFile) {
-          //noinspection ConstantConditions
-          final List<RatedResolveResult> resolved = ((PyFile)initPy).multiResolveName(((PsiNamedElement)toplevel).getName());
-          final PsiElement finalTopLevel = toplevel;
-          if (resolved.stream().anyMatch(r -> r.getElement() == finalTopLevel)) {
-            virtualFile = dir.getVirtualFile();
+      VirtualFile virtualFile = srcfile.getVirtualFile();
+      if (virtualFile == null) {
+        return null;
+      }
+      if (srcfile instanceof PsiFile && symbol instanceof PsiNamedElement && !(symbol instanceof PsiFileSystemItem)) {
+        PsiElement toplevel = symbol;
+        if (symbol instanceof PyFunction) {
+          final PyClass containingClass = ((PyFunction)symbol).getContainingClass();
+          if (containingClass != null) {
+            toplevel = containingClass;
           }
         }
-        dir = dir.getParentDirectory();
-      }
-    }
-    final QualifiedName qname = findShortestImportableQName(foothold != null ? foothold : symbol, virtualFile);
-    if (qname != null) {
-      for (PyCanonicalPathProvider provider : Extensions.getExtensions(PyCanonicalPathProvider.EP_NAME)) {
-        final QualifiedName restored = provider.getCanonicalPath(qname, foothold);
-        if (restored != null) {
-          return restored;
+        PsiDirectory dir = ((PsiFile)srcfile).getContainingDirectory();
+        while (dir != null) {
+          PsiFile initPy = dir.findFile(PyNames.INIT_DOT_PY);
+          if (initPy == null) {
+            break;
+          }
+          if (initPy instanceof PyFile) {
+            //noinspection ConstantConditions
+            final List<RatedResolveResult> resolved = ((PyFile)initPy).multiResolveName(((PsiNamedElement)toplevel).getName());
+            final PsiElement finalTopLevel = toplevel;
+            if (resolved.stream().anyMatch(r -> r.getElement() == finalTopLevel)) {
+              virtualFile = dir.getVirtualFile();
+            }
+          }
+          dir = dir.getParentDirectory();
         }
       }
-    }
-    return qname;
+      final QualifiedName qname = findShortestImportableQName(param != null ? param : symbol, virtualFile);
+      if (qname != null) {
+        for (PyCanonicalPathProvider provider : Extensions.getExtensions(PyCanonicalPathProvider.EP_NAME)) {
+          final QualifiedName restored = provider.getCanonicalPath(qname, param);
+          if (restored != null) {
+            return restored;
+          }
+        }
+      }
+      return qname;
+    });
   }
 
   @Nullable