diff --git a/platform/core-api/src/com/intellij/openapi/vfs/VfsUtilCore.java b/platform/core-api/src/com/intellij/openapi/vfs/VfsUtilCore.java
index 6e0b38c3bb6a..fd21a442916e 100644
--- a/platform/core-api/src/com/intellij/openapi/vfs/VfsUtilCore.java
+++ b/platform/core-api/src/com/intellij/openapi/vfs/VfsUtilCore.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2016 JetBrains s.r.o.
+ * Copyright 2000-2017 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.
@@ -467,7 +467,7 @@ public class VfsUtilCore {
         throw new RuntimeException(new IOException(VfsBundle.message("url.parse.error", url.toExternalForm())));
       }
     }
-    if (SystemInfo.isWindows || SystemInfo.isOS2) {
+    if (SystemInfo.isWindows) {
       while (!path.isEmpty() && path.charAt(0) == '/') {
         path = path.substring(1, path.length());
       }
diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/LocalFileSystemBase.java b/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/LocalFileSystemBase.java
index 0387ca2b2d58..204024bd8595 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/LocalFileSystemBase.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/LocalFileSystemBase.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2016 JetBrains s.r.o.
+ * Copyright 2000-2017 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.
@@ -72,14 +72,13 @@ public abstract class LocalFileSystemBase extends LocalFileSystem {
 
   @Override
   public VirtualFile findFileByIoFile(@NotNull File file) {
-    String path = FileUtil.toSystemIndependentName(file.getAbsolutePath());
-    return findFileByPath(path);
+    return findFileByPath(FileUtil.toSystemIndependentName(file.getAbsolutePath()));
   }
 
   @NotNull
   protected static File convertToIOFile(@NotNull final VirtualFile file) {
     String path = file.getPath();
-    if (StringUtil.endsWithChar(path, ':') && path.length() == 2 && (SystemInfo.isWindows || SystemInfo.isOS2)) {
+    if (StringUtil.endsWithChar(path, ':') && path.length() == 2 && SystemInfo.isWindows) {
       path += "/"; // Make 'c:' resolve to a root directory for drive c:, not the current directory on that drive
     }
 
diff --git a/platform/util-rt/src/com/intellij/openapi/util/SystemInfoRt.java b/platform/util-rt/src/com/intellij/openapi/util/SystemInfoRt.java
index 3ed08ab5f207..beba4e3bb270 100644
--- a/platform/util-rt/src/com/intellij/openapi/util/SystemInfoRt.java
+++ b/platform/util-rt/src/com/intellij/openapi/util/SystemInfoRt.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2016 JetBrains s.r.o.
+ * Copyright 2000-2017 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.
@@ -29,13 +29,17 @@ public class SystemInfoRt {
 
   private static final String _OS_NAME = OS_NAME.toLowerCase(Locale.US);
   public static final boolean isWindows = _OS_NAME.startsWith("windows");
-  public static final boolean isOS2 = _OS_NAME.startsWith("os/2") || _OS_NAME.startsWith("os2");
   public static final boolean isMac = _OS_NAME.startsWith("mac");
   public static final boolean isLinux = _OS_NAME.startsWith("linux");
   public static final boolean isFreeBSD = _OS_NAME.startsWith("freebsd");
   public static final boolean isSolaris = _OS_NAME.startsWith("sunos");
-  public static final boolean isUnix = !isWindows && !isOS2;
+  public static final boolean isUnix = !isWindows;
 
   public static final boolean isFileSystemCaseSensitive =
     isUnix && !isMac || "true".equalsIgnoreCase(System.getProperty("idea.case.sensitive.fs"));
+
+  //<editor-fold desc="Deprecated stuff.">
+  /** @deprecated outdated (to be removed in IDEA 2018) */
+  public static final boolean isOS2 = _OS_NAME.startsWith("os/2") || _OS_NAME.startsWith("os2");
+  //</editor-fold>
 }
\ No newline at end of file
diff --git a/platform/util/src/com/intellij/openapi/util/SystemInfo.java b/platform/util/src/com/intellij/openapi/util/SystemInfo.java
index 3c4f065d0d37..1d1d0c0f5aa4 100644
--- a/platform/util/src/com/intellij/openapi/util/SystemInfo.java
+++ b/platform/util/src/com/intellij/openapi/util/SystemInfo.java
@@ -37,7 +37,6 @@ public class SystemInfo extends SystemInfoRt {
 
   public static final boolean isWindows = SystemInfoRt.isWindows;
   public static final boolean isMac = SystemInfoRt.isMac;
-  public static final boolean isOS2 = SystemInfoRt.isOS2;
   public static final boolean isLinux = SystemInfoRt.isLinux;
   public static final boolean isFreeBSD = SystemInfoRt.isFreeBSD;
   public static final boolean isSolaris = SystemInfoRt.isSolaris;
@@ -238,5 +237,8 @@ public class SystemInfo extends SystemInfoRt {
   public static String getUnixReleaseVersion() {
     return null;
   }
+
+  /** @deprecated outdated (to be removed in IDEA 2018) */
+  public static final boolean isOS2 = SystemInfoRt.isOS2;
   //</editor-fold>
 }
\ No newline at end of file
diff --git a/python/src/com/jetbrains/python/buildout/BuildoutFacet.java b/python/src/com/jetbrains/python/buildout/BuildoutFacet.java
index bbf307e51716..41464dd71eb2 100644
--- a/python/src/com/jetbrains/python/buildout/BuildoutFacet.java
+++ b/python/src/com/jetbrains/python/buildout/BuildoutFacet.java
@@ -99,7 +99,7 @@ public class BuildoutFacet extends LibraryContributingFacet<BuildoutFacetConfigu
             bin.refresh(false, false);
           }
           final String exe;
-          if (SystemInfo.isWindows || SystemInfo.isOS2) {
+          if (SystemInfo.isWindows) {
             exe = "buildout.exe";
           }
           else {
diff --git a/python/src/com/jetbrains/python/sdk/PythonSdkType.java b/python/src/com/jetbrains/python/sdk/PythonSdkType.java
index 34a2c34bf748..4c350e72ad2c 100644
--- a/python/src/com/jetbrains/python/sdk/PythonSdkType.java
+++ b/python/src/com/jetbrains/python/sdk/PythonSdkType.java
@@ -375,7 +375,7 @@ public final class PythonSdkType extends SdkType {
    */
   @Nullable
   public static File findExecutableFile(File parent, String name) {
-    if (SystemInfo.isWindows || SystemInfo.isOS2) {
+    if (SystemInfo.isWindows) {
       for (String suffix : WINDOWS_EXECUTABLE_SUFFIXES) {
         File file = new File(parent, name + "." + suffix);
         if (file.exists()) return file;