diff --git a/backend_tcl/readme.txt b/backend_tcl/readme.txt
index c60495ad..a9bfb028 100644
--- a/backend_tcl/readme.txt
+++ b/backend_tcl/readme.txt
@@ -11,13 +11,20 @@ Build:
 The header files of a Tcl and Tk build are required for the build.
 They are included in a Tcl/Tk source tree or in an installed Tcl/Tk.
 
-There are 3 build environments available:
+There are the standard TCL build environments available:
 
 - configure based build system for Linux/macOS and MSYS/Cygwin/MSYS2 (Windows)
   (contributed by Christian Werner) - see "docs/manual.txt" Annex C for details
 - "win\makefile.vc" for Microsoft Visual Studio command prompt (nmake) - see
   "win\README.txt" for details
-- "zint_tcl.vcxproj" for Microsoft Visual C++ 2022 interactive build
+
+The GS1 syntax engine may be added optionally.
+https://github.com/gs1/gs1-syntax-engine
+Please look to the top of makefile.vc to activate it.
+
+The GS1 syntax engine project currently only allows to build a dll and an import lib.
+This hopefully changes in future.
+Remark, that the syntax engine dll may not be included in a starkit or zipkit.
 
 Usage:
 
diff --git a/backend_tcl/win/makefile.vc b/backend_tcl/win/makefile.vc
index 9c9e7aaa..881d1c55 100644
--- a/backend_tcl/win/makefile.vc
+++ b/backend_tcl/win/makefile.vc
@@ -18,6 +18,17 @@
 #
 #------------------------------------------------------------------------------
 
+# Activate GS1 syntax engine support (option "-gs1strict")
+# https://github.com/gs1/gs1-syntax-engine
+# Build the library gs1encoders.dll
+ZINT_HAVE_GS1SE = 0
+
+# folder of the include file gs1encoders.h (in src/c-lib folder of the syntax engine)
+SYNTAX_ENGINE_INCLUDE = $(ROOT)\..\..\gs1-syntax-engine-main\src\c-lib
+
+# folder of the library gs1encoders.lib of the syntax engine
+SYNTAX_ENGINE_LIB = $(ROOT)\..\..\gs1-syntax-engine-main\src\c-lib\build\library\x64\Release
+
 # The name of the package
 PROJECT = zint
 PROJECT_REQUIRES_TK = 1
@@ -94,11 +105,14 @@ PRJ_OBJS = \
 PRJ_DEFINES = -D_CRT_SECURE_NO_DEPRECATE
 PRJ_DEFINES = $(PRJ_DEFINES) -DZINT_NO_PNG=1
 # PRJ_DEFINES = $(PRJ_DEFINES) -DZINT_VERSION=PACKAGE_VERSION
-PRJ_DEFINES = $(PRJ_DEFINES) -I$(TMP_DIR)
-PRJ_DEFINES = $(PRJ_DEFINES) -I$(BACKEND_DIR)
-
-
+PRJ_INCLUDES = -I$(TMP_DIR)
+PRJ_INCLUDES = $(PRJ_INCLUDES) -I$(BACKEND_DIR)
 
+!if $(ZINT_HAVE_GS1SE)
+PRJ_DEFINES = $(PRJ_DEFINES) -DZINT_HAVE_GS1SE=1
+PRJ_INCLUDES = $(PRJ_INCLUDES) -I$(SYNTAX_ENGINE_INCLUDE)
+PRJ_LIBS = $(SYNTAX_ENGINE_LIB)\gs1encoders.lib
+!endif
 
 # Define the standard targets
 !include "$(_RULESDIR)\targets.vc"
diff --git a/backend_tcl/zint.c b/backend_tcl/zint.c
index 26cd1292..7183200a 100644
--- a/backend_tcl/zint.c
+++ b/backend_tcl/zint.c
@@ -577,7 +577,9 @@ static const char help_message[] = "zint tcl(stub,obj) dll\n"
     "   -gs1nocheck bool: for gs1, do not check validity of data (allows non-standard symbols)\n"
     "   -gs1parens bool: for gs1, AIs enclosed in parentheses instead of square brackets\n"
 #ifdef ZINT_HAVE_GS1SE
-    "   -gs1strict bool: Use GS1 Syntax Engine to strictly validate GS1 data\n"
+    "   -gs1strict bool: use GS1 Syntax Engine to strictly validate GS1 data\n"
+#else
+    "   -gs1strict 0: GS1 syntax engine not compiled in, may not be activated.\n"
 #endif
     "   -gssep bool: for gs1, use gs as separator instead fnc1 (Datamatrix only)\n"
     "   -guarddescent double: Height of guard bar descent in modules (EAN/UPC only)\n"
@@ -904,9 +906,7 @@ static int Encode(Tcl_Interp *interp, int objc,
             "-cols", "-compliantheight", "-dmiso144", "-dmre", "-dotsize", "-dotty",
             "-eci", "-esc", "-extraesc", "-fast", "-fg", "-format", "-fullmultibyte",
             "-gs1nocheck", "-gs1parens",
-#ifdef ZINT_HAVE_GS1SE
             "-gs1strict",
-#endif
             "-gssep", "-guarddescent",
             "-guardwhitespace", "-height", "-heightperrow", "-init", "-mask", "-mode",
             "-nobackground", "-noquietzones", "-notext", "-primary", "-quietzones",
@@ -920,9 +920,7 @@ static int Encode(Tcl_Interp *interp, int objc,
             iCols, iCompliantHeight, iDMISO144, iDMRE, iDotSize, iDotty,
             iECI, iEsc, iExtraEsc, iFast, iFG, iFormat, iFullMultiByte,
             iGS1NoCheck, iGS1Parens,
-#ifdef ZINT_HAVE_GS1SE
             iGS1Strict,
-#endif
             iGSSep, iGuardDescent,
             iGuardWhitespace, iHeight, iHeightPerRow, iInit, iMask, iMode,
             iNoBackground, iNoQuietZones, iNoText, iPrimary, iQuietZones,
@@ -959,9 +957,7 @@ static int Encode(Tcl_Interp *interp, int objc,
         case iFast:
         case iGS1NoCheck:
         case iGS1Parens:
-#ifdef ZINT_HAVE_GS1SE
         case iGS1Strict:
-#endif
         case iGSSep:
         case iGuardWhitespace:
         case iHeightPerRow:
@@ -1170,16 +1166,20 @@ static int Encode(Tcl_Interp *interp, int objc,
                 my_symbol->input_mode &= ~GS1PARENS_MODE;
             }
             break;
-#ifdef ZINT_HAVE_GS1SE
         case iGS1Strict:
             if (intValue) {
+#ifdef ZINT_HAVE_GS1SE
                 my_symbol->input_mode |= GS1SYNTAXENGINE_MODE;
                 my_symbol->input_mode = (my_symbol->input_mode & ~0x07) | GS1_MODE; /* Now sets GS1_MODE also */
+#else
+                Tcl_SetObjResult(interp,
+                    Tcl_NewStringObj("GS1 syntax engine not compiled in", -1));
+                fError = 1;
+#endif
             } else {
                 my_symbol->input_mode &= ~GS1SYNTAXENGINE_MODE;
             }
             break;
-#endif
         case iGSSep:
             if (intValue) {
                 my_symbol->output_options |= GS1_GS_SEPARATOR;