diff --git a/win32/php4dll.dsp b/win32/php4dll.dsp
index 2cc4b8335b0..51872c2ef13 100644
--- a/win32/php4dll.dsp
+++ b/win32/php4dll.dsp
@@ -185,6 +185,10 @@ SOURCE=..\main\php_variables.c
 # End Source File
 # Begin Source File
 
+SOURCE=..\ext\standard\proc_open.c
+# End Source File
+# Begin Source File
+
 SOURCE=..\ext\standard\quot_print.c
 # End Source File
 # Begin Source File
diff --git a/win32/php4dllts.dsp b/win32/php4dllts.dsp
index bf8b1b62a72..1818eeb35de 100644
--- a/win32/php4dllts.dsp
+++ b/win32/php4dllts.dsp
@@ -223,6 +223,10 @@ SOURCE=..\main\php_variables.c
 # End Source File
 # Begin Source File
 
+SOURCE=..\ext\standard\proc_open.c
+# End Source File
+# Begin Source File
+
 SOURCE=..\ext\standard\quot_print.c
 # End Source File
 # Begin Source File