diff --git a/dlls/kernel32/process.c b/dlls/kernel32/process.c
index 70c38ebdf0d..5b8a3d335e7 100644
--- a/dlls/kernel32/process.c
+++ b/dlls/kernel32/process.c
@@ -745,6 +745,10 @@ static void update_library_argv0( const WCHAR *argv0 )
  *   resulting in an odd number of '\' followed by a '"'
  *   '\"'    -> '\\\"'
  *   '\\"'   -> '\\\\\"'
+ * - '\'s are followed by the closing '"' must be doubled,
+ *   resulting in an even number of '\' followed by a '"'
+ *   ' \'    -> '" \\"'
+ *   ' \\'    -> '" \\\\"'
  * - '\'s that are not followed by a '"' can be left as is
  *   'a\b'   == 'a\b'
  *   'a\\b'  == 'a\\b'
@@ -787,7 +791,7 @@ static BOOL build_command_line( WCHAR **argv )
         }
         len+=(a-*arg)+1 /* for the separating space */;
         if (has_space)
-            len+=2; /* for the quotes */
+            len+=2+bcount; /* for the quotes and doubling of '\' preceding the closing quote */
     }
 
     if (!(rupp->CommandLine.Buffer = RtlAllocateHeap( GetProcessHeap(), 0, len * sizeof(WCHAR))))
@@ -800,6 +804,7 @@ static BOOL build_command_line( WCHAR **argv )
     {
         BOOL has_space,has_quote;
         WCHAR* a;
+        int bcount;
 
         /* Check for quotes and spaces in this argument */
         has_space=has_quote=FALSE;
@@ -821,9 +826,7 @@ static BOOL build_command_line( WCHAR **argv )
         /* Now transfer it to the command line */
         if (has_space)
             *p++='"';
-        if (has_quote) {
-            int bcount;
-
+        if (has_quote || has_space) {
             bcount=0;
             a=*arg;
             while (*a!='\0') {
@@ -849,8 +852,14 @@ static BOOL build_command_line( WCHAR **argv )
             WCHAR* x = *arg;
             while ((*p=*x++)) p++;
         }
-        if (has_space)
+        if (has_space) {
+            int i;
+
+            /* Double all the '\' preceding the closing quote */
+            for (i=0;i<bcount;i++)
+                *p++='\\';
             *p++='"';
+        }
         *p++=' ';
     }
     if (p > rupp->CommandLine.Buffer)