diff --git a/CMakeLists.txt b/CMakeLists.txt
index e0a8061974..56441a21f2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -257,6 +257,14 @@ if(BUILD_DOTNET)
   option(UNIVERSAL_DOTNET_PACKAGE "Build a .Net multi OS Package" OFF)
   message(STATUS ".Net: Create multiple os package: ${UNIVERSAL_DOTNET_PACKAGE}")
 
+  # Language Version
+  # see: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/configure-language-version
+  set(DOTNET_LANG "9.0" CACHE STRING "Specify the C# language version (default \"9.0\")")
+  message(STATUS ".Net C# language version: ${DOTNET_LANG}")
+
+  set(DOTNET_SAMPLE_LANG "8.0" CACHE STRING "Specify the C# language version for samples (default \"8.0\")")
+  message(STATUS ".Net C# language version: ${DOTNET_SAMPLE_LANG}")
+
   option(USE_DOTNET_48 "Use .Net Framework 4.8 support" OFF)
   message(STATUS ".Net: Use .Net Framework 4.8 support: ${USE_DOTNET_48}")
 
diff --git a/cmake/dotnet.cmake b/cmake/dotnet.cmake
index 59f7a772e0..99ebb33f71 100644
--- a/cmake/dotnet.cmake
+++ b/cmake/dotnet.cmake
@@ -68,11 +68,6 @@ message(STATUS ".Net runtime project: ${DOTNET_NATIVE_PROJECT}")
 set(DOTNET_NATIVE_PROJECT_DIR ${PROJECT_BINARY_DIR}/dotnet/${DOTNET_NATIVE_PROJECT})
 message(STATUS ".Net runtime project build path: ${DOTNET_NATIVE_PROJECT_DIR}")
 
-# Language Version
-# see: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/configure-language-version
-set(DOTNET_LANG "9.0")
-message(STATUS ".Net C# language version: ${DOTNET_LANG}")
-
 # Targeted Framework Moniker
 # see: https://docs.microsoft.com/en-us/dotnet/standard/frameworks
 # see: https://learn.microsoft.com/en-us/dotnet/standard/net-standard
diff --git a/makefiles/Makefile.dotnet.mk b/makefiles/Makefile.dotnet.mk
index 770730cc8a..49a480fb37 100644
--- a/makefiles/Makefile.dotnet.mk
+++ b/makefiles/Makefile.dotnet.mk
@@ -108,7 +108,7 @@ $(TEMP_DOTNET_DIR)/$1/%/%.csproj: \
 	$(SED) -e "s/@DOTNET_PACKAGES_DIR@/..\/..\/..\/$(BUILD_DIR)\/dotnet\/packages/" \
  ortools$Sdotnet$SSample.csproj.in \
  > $(TEMP_DOTNET_DIR)$S$1$S$$*$S$$*.csproj
-	$(SED) -i -e 's/@DOTNET_LANG@/9.0/' \
+	$(SED) -i -e 's/@DOTNET_SAMPLE_LANG@/9.0/' \
  $(TEMP_DOTNET_DIR)$S$1$S$$*$S$$*.csproj
 ifeq ($(USE_DOTNET_6)_$(USE_DOTNET_CORE_31),ON_ON)
 	$(SED) -i -e 's/@DOTNET_TFM@/<TargetFrameworks>netcoreapp3.1;net6.0<\/TargetFrameworks>/' \
@@ -180,7 +180,7 @@ $(TEMP_DOTNET_DIR)/$1/%/%.csproj: \
 	$(SED) -e "s/@DOTNET_PACKAGES_DIR@/..\/..\/..\/$(BUILD_DIR)\/dotnet\/packages/" \
  ortools$Sdotnet$SSample.csproj.in \
  > $(TEMP_DOTNET_DIR)$S$1$S$$*$S$$*.csproj
-	$(SED) -i -e 's/@DOTNET_LANG@/9.0/' \
+	$(SED) -i -e 's/@DOTNET_SAMPLE_LANG@/9.0/' \
  $(TEMP_DOTNET_DIR)$S$1$S$$*$S$$*.csproj
 ifeq ($(USE_DOTNET_6)_$(USE_DOTNET_CORE_31),ON_ON)
 	$(SED) -i -e 's/@DOTNET_TFM@/<TargetFrameworks>netcoreapp3.1;net6.0<\/TargetFrameworks>/' \
@@ -653,7 +653,7 @@ $(TEMP_DOTNET_DIR)/ortools_examples/examples/dotnet/%.csproj: \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
 	$(SED) -i -e 's/@DOTNET_PACKAGES_DIR@/./' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
-	$(SED) -i -e 's/@DOTNET_LANG@/9.0/' \
+	$(SED) -i -e 's/@DOTNET_SAMPLE_LANG@/9.0/' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
 	$(SED) -i -e 's/@DOTNET_TFM@/<TargetFrameworks>netcoreapp3.1;net6.0<\/TargetFrameworks>/' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
@@ -686,7 +686,7 @@ $(TEMP_DOTNET_DIR)/ortools_examples/examples/dotnet/%.csproj: \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
 	$(SED) -i -e 's/@DOTNET_PACKAGES_DIR@/./' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
-	$(SED) -i -e 's/@DOTNET_LANG@/9.0/' \
+	$(SED) -i -e 's/@DOTNET_SAMPLE_LANG@/9.0/' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
 	$(SED) -i -e 's/@DOTNET_TFM@/<TargetFrameworks>netcoreapp3.1;net6.0<\/TargetFrameworks>/' \
  $(TEMP_DOTNET_DIR)$Sortools_examples$Sexamples$Sdotnet$S$$*.csproj
diff --git a/ortools/dotnet/Sample.csproj.in b/ortools/dotnet/Sample.csproj.in
index d13eae05bc..3d9802fa5c 100644
--- a/ortools/dotnet/Sample.csproj.in
+++ b/ortools/dotnet/Sample.csproj.in
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <LangVersion>8.0</LangVersion>
+    <LangVersion>@DOTNET_SAMPLE_LANG@</LangVersion>
     @DOTNET_TFM@
     <EnableDefaultItems>false</EnableDefaultItems>
     <EnableDefaultCompileItems>false</EnableDefaultCompileItems>