diff --git a/Docs/src/compiler.but b/Docs/src/compiler.but
index a4fb4311..c908e054 100644
--- a/Docs/src/compiler.but
+++ b/Docs/src/compiler.but
@@ -6,14 +6,15 @@ These commands are similar to the C preprocessor in terms of purpose and functio
 
 \S1{include} !include
 
-\c file
+\c [/NONFATAL] file
 
-This command will include 'file' as if it was part of the original script. Note that if a file is included in another directory, the current directory is still where the script was compiled from (not where the included file resides). If the compiler can't find the file it will look for it in every include directory. See \R{addincludedir}{!addincludedir} for more information.
+This command will include 'file' as if it was part of the original script. Note that if a file is included in another directory, the current directory is still where the script was compiled from (not where the included file resides). If the compiler can't find the file it will look for it in every include directory. See \R{addincludedir}{!addincludedir} for more information. If the /nonfatal switch is used and no files are found, a warning will be issued instead of an error.
 
 \c !include WinMessages.nsh
 \c !include Library.nsh
-\c !include MyConfig.nsh
+\c !include C:\MyConfig.nsi
 \c !include ..\MyConfig.nsh
+\c !include /NONFATAL file_that_may_exist_or_not.nsh
 
 \S1{addincludedir} !addincludedir
 
diff --git a/Source/Tests/preprocessor.nsi b/Source/Tests/preprocessor.nsi
index 6a11ceb4..cfcc6ef1 100644
--- a/Source/Tests/preprocessor.nsi
+++ b/Source/Tests/preprocessor.nsi
@@ -1,3 +1,6 @@
+!ifndef file_is_included
+!define file_is_included
+
 Name preprocessor
 OutFile preprocessor.exe
 
@@ -48,5 +51,16 @@ d\
 i\
 f
 
+# this should just give a warning, not an error
+!include /NONFATAL file_that_doesnt_exist.nsh
+
+# this should include this file just one time.
+!include preprocessor.nsi
+
 Section
 SectionEnd
+
+!else
+# this should just give a warning, not an error
+!include /NONFATAL another_file_that_doesnt_exist.nsh
+!endif
diff --git a/Source/script.cpp b/Source/script.cpp
index ec42fd98..b0577c90 100644
--- a/Source/script.cpp
+++ b/Source/script.cpp
@@ -2745,7 +2745,20 @@ int CEXEBuild::doCommand(int which_token, LineParser &line)
     return PS_OK;
     case TOK_P_INCLUDE:
       {
+        bool required = true;
+
         char *f = line.gettoken_str(1);
+
+        if(!stricmp(f,"/nonfatal")) {
+          if (line.getnumtokens()!=3)
+            PRINTHELP();
+
+          f = line.gettoken_str(2);
+          required = false;
+        } else if (line.getnumtokens()!=2) {
+          PRINTHELP();
+        }
+
 #ifdef _WIN32
         char *fc = f;
 #else
@@ -2820,8 +2833,12 @@ int CEXEBuild::doCommand(int which_token, LineParser &line)
         // nothing found
         if (!included)
         {
-          ERROR_MSG("!include: could not find: \"%s\"\n",f);
-          return PS_ERROR;
+          if(required) {
+            ERROR_MSG("!include: could not find: \"%s\"\n",f);
+            return PS_ERROR;
+          } else {
+            warning_fl("!include: could not find: \"%s\"",f);
+          }
         }
       }
     return PS_OK;
diff --git a/Source/tokens.cpp b/Source/tokens.cpp
index 904495f2..b2a2cef7 100644
--- a/Source/tokens.cpp
+++ b/Source/tokens.cpp
@@ -222,7 +222,7 @@ static tokenType tokenlist[TOK__LAST] =
 {TOK_P_SYSTEMEXEC,"!system",1,2,"command [<|>|<>|=) retval]",TP_ALL},
 {TOK_P_EXECUTE,"!execute",1,0,"command",TP_ALL},
 {TOK_P_ADDINCLUDEDIR,"!AddIncludeDir",1,0,"dir",TP_ALL},
-{TOK_P_INCLUDE,"!include",1,0,"filename.nsi",TP_ALL},
+{TOK_P_INCLUDE,"!include",1,1,"[/NONFATAL] filename.nsh",TP_ALL},
 {TOK_P_CD,"!cd",1,0,"absolute_or_relative_new_directory",TP_ALL},
 {TOK_P_IFDEF,"!ifdef",1,-1,"symbol [| symbol2 [& symbol3 [...]]]",TP_ALL},
 {TOK_P_IFNDEF,"!ifndef",1,-1,"symbol [| symbol2 [& symbol3 [...]]]",TP_ALL},