diff --git a/src/common/attributes/attributes.vcproj b/src/common/attributes/attributes.vcproj
index cf1996012..050b4fc05 100644
--- a/src/common/attributes/attributes.vcproj
+++ b/src/common/attributes/attributes.vcproj
@@ -79,7 +79,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/gamecode/gamecode.vcproj b/src/common/gamecode/gamecode.vcproj
index 95a6f80e7..eaee06922 100644
--- a/src/common/gamecode/gamecode.vcproj
+++ b/src/common/gamecode/gamecode.vcproj
@@ -25,7 +25,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/items/items.vcproj b/src/common/items/items.vcproj
index 2ed16b4f3..5ea120931 100644
--- a/src/common/items/items.vcproj
+++ b/src/common/items/items.vcproj
@@ -24,7 +24,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/kernel/calendar.c b/src/common/kernel/calendar.c
index e87b60451..4255b3074 100644
--- a/src/common/kernel/calendar.c
+++ b/src/common/kernel/calendar.c
@@ -13,7 +13,7 @@ int  *month_season = NULL;
 char *agename = NULL;
 int  seasons = 0;
 
-gamedate *
+const gamedate *
 get_gamedate(int turn, gamedate * gd)
 {
   static gamedate staticdate;
diff --git a/src/common/kernel/calendar.h b/src/common/kernel/calendar.h
index 323ca68a2..45bb067a5 100644
--- a/src/common/kernel/calendar.h
+++ b/src/common/kernel/calendar.h
@@ -28,7 +28,7 @@ typedef struct gamedate {
   int week;
 } gamedate;
 
-extern gamedate * get_gamedate(int turn, gamedate * gd);
+extern const gamedate * get_gamedate(int turn, gamedate * gd);
 extern void calendar_cleanup(void);
 
 #ifdef __cplusplus
diff --git a/src/common/kernel/kernel.vcproj b/src/common/kernel/kernel.vcproj
index 9e57e956b..1ec7e310d 100644
--- a/src/common/kernel/kernel.vcproj
+++ b/src/common/kernel/kernel.vcproj
@@ -130,7 +130,7 @@
 				AdditionalIncludeDirectories="../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/modules/modules.vcproj b/src/common/modules/modules.vcproj
index ed0f8cd1f..8ddbe19b7 100644
--- a/src/common/modules/modules.vcproj
+++ b/src/common/modules/modules.vcproj
@@ -78,7 +78,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/races/races.vcproj b/src/common/races/races.vcproj
index b42ef11da..84d2dd91d 100644
--- a/src/common/races/races.vcproj
+++ b/src/common/races/races.vcproj
@@ -78,7 +78,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/spells/spells.vcproj b/src/common/spells/spells.vcproj
index c428e3cca..e3296325d 100644
--- a/src/common/spells/spells.vcproj
+++ b/src/common/spells/spells.vcproj
@@ -24,7 +24,7 @@
 				AdditionalIncludeDirectories="../kernel,../util,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/triggers/triggers.vcproj b/src/common/triggers/triggers.vcproj
index 85ef672c1..14ba3ee43 100644
--- a/src/common/triggers/triggers.vcproj
+++ b/src/common/triggers/triggers.vcproj
@@ -78,7 +78,7 @@
 				AdditionalIncludeDirectories="../util,../kernel,../..,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/common/util/util.vcproj b/src/common/util/util.vcproj
index a76c921f5..3b943754f 100644
--- a/src/common/util/util.vcproj
+++ b/src/common/util/util.vcproj
@@ -24,7 +24,7 @@
 				AdditionalIncludeDirectories="../.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_WINDOWS"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/eressea/eressea-lua.vcproj b/src/eressea/eressea-lua.vcproj
index ba2f19dcd..b4cfe8f76 100644
--- a/src/eressea/eressea-lua.vcproj
+++ b/src/eressea/eressea-lua.vcproj
@@ -27,7 +27,7 @@
 				AdditionalIncludeDirectories="../common/kernel,../common/gamecode,../common/util,../common,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_CONSOLE"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="FALSE"
 				UsePrecompiledHeader="2"
diff --git a/src/eressea/eressea.vcproj b/src/eressea/eressea.vcproj
index 8a8a35498..4665c16c0 100644
--- a/src/eressea/eressea.vcproj
+++ b/src/eressea/eressea.vcproj
@@ -26,7 +26,7 @@
 				AdditionalIncludeDirectories="../common/kernel,../common/gamecode,../common/util,../common,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_CONSOLE"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"
diff --git a/src/mapper/mapper.vcproj b/src/mapper/mapper.vcproj
index d859cb331..08bc7b03f 100644
--- a/src/mapper/mapper.vcproj
+++ b/src/mapper/mapper.vcproj
@@ -25,7 +25,7 @@
 				AdditionalIncludeDirectories="../common/kernel,../common/gamecode,../common/util,../common,.."
 				PreprocessorDefinitions="WIN32,NDEBUG,_CONSOLE"
 				StringPooling="TRUE"
-				RuntimeLibrary="2"
+				RuntimeLibrary="4"
 				EnableFunctionLevelLinking="TRUE"
 				DisableLanguageExtensions="TRUE"
 				UsePrecompiledHeader="2"