diff --git a/python/openapi/src/com/jetbrains/python/packaging/PyRequirement.java b/python/openapi/src/com/jetbrains/python/packaging/PyRequirement.java
index 0e101234b6b4..1d027e8ce64e 100644
--- a/python/openapi/src/com/jetbrains/python/packaging/PyRequirement.java
+++ b/python/openapi/src/com/jetbrains/python/packaging/PyRequirement.java
@@ -333,7 +333,7 @@ public class PyRequirement {
   }
 
   @NotNull
-  private static PyRequirementVersionSpec calculateVersionSpec(@NotNull String version, @NotNull PyRequirementRelation expectedRelation) {
+  public static PyRequirementVersionSpec calculateVersionSpec(@NotNull String version, @NotNull PyRequirementRelation expectedRelation) {
     final String normalizedVersion = PyRequirementVersionNormalizer.normalize(version);
 
     return normalizedVersion == null ?
diff --git a/python/src/com/jetbrains/python/packaging/ui/PyPackageManagementService.java b/python/src/com/jetbrains/python/packaging/ui/PyPackageManagementService.java
index 64a686eec688..21f1ac4590a7 100644
--- a/python/src/com/jetbrains/python/packaging/ui/PyPackageManagementService.java
+++ b/python/src/com/jetbrains/python/packaging/ui/PyPackageManagementService.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@ import com.intellij.webcore.packaging.PackageManagementServiceEx;
 import com.intellij.webcore.packaging.RepoPackage;
 import com.jetbrains.python.packaging.*;
 import com.jetbrains.python.packaging.PyPIPackageUtil.PackageDetails;
+import com.jetbrains.python.packaging.requirement.PyRequirementRelation;
 import com.jetbrains.python.psi.LanguageLevel;
 import com.jetbrains.python.sdk.PySdkUtil;
 import com.jetbrains.python.sdk.PythonSdkType;
@@ -386,4 +387,14 @@ public class PyPackageManagementService extends PackageManagementServiceEx {
       }
     });
   }
+
+  @Override
+  public int compareVersions(@NotNull String version1, @NotNull String version2) {
+    if (PyRequirement.calculateVersionSpec(version2, PyRequirementRelation.EQ).matches(version1)) {
+      // Here we're catching the case described in PY-20939.
+      // The order of 'version1' and 'version2' is important: version2 is an available version which version1 tries to match
+      return 0;
+    }
+    return super.compareVersions(version1, version2);
+  }
 }
\ No newline at end of file