diff --git a/Lib/distutils/msvc9compiler.py b/Lib/distutils/msvc9compiler.py
index fdb74ae..465013d 100644
--- a/Lib/distutils/msvc9compiler.py
+++ b/Lib/distutils/msvc9compiler.py
@@ -193,6 +193,17 @@
             reduced_paths.append(np)
     return reduced_paths
 
+def removeDuplicates(variable):
+    """Remove duplicate values of an environment variable.
+    """
+    oldList = variable.split(os.pathsep)
+    newList = []
+    for i in oldList:
+        if i not in newList:
+            newList.append(i)
+    newVariable = os.pathsep.join(newList)
+    return newVariable
+
 def find_vcvarsall(version):
     """Find the vcvarsall.bat file
 
@@ -252,12 +263,12 @@
         if '=' not in line:
             continue
         line = line.strip()
-        key, value = line.split('=')
+        key, value = line.split('=', 1)
         key = key.lower()
         if key in interesting:
             if value.endswith(os.pathsep):
                 value = value[:-1]
-            result[key] = value
+            result[key] = removeDuplicates(value)
 
     if len(result) != len(interesting):
         raise ValueError(str(list(result.keys())))
diff --git a/Misc/NEWS b/Misc/NEWS
index d1be39c..355633d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -74,6 +74,10 @@
 Extension Modules
 -----------------
 
+- Issue #2975: When compiling several extension modules with Visual Studio 2008
+  from the same python interpreter, some environment variables would grow
+  without limit.
+
 - Issue #3643: Added a few more checks to _testcapi to prevent segfaults by
   exploitation of poor argument checking.