diff --git a/include/msvcrt/crtdbg.h b/include/msvcrt/crtdbg.h
index 3b2f1121735..a4393a9aab4 100644
--- a/include/msvcrt/crtdbg.h
+++ b/include/msvcrt/crtdbg.h
@@ -77,6 +77,10 @@ typedef struct _CrtMemState
 #define _CrtDbgBreak()                  ((void)0)
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 extern int _crtAssertBusy;
 extern int _crtBreakAlloc;
 extern int _crtDbgFlag;
@@ -90,6 +94,10 @@ int   _CrtSetDbgFlag(int new);
 void *_CrtSetDumpClient(void *dumpClient);
 int   _CrtSetReportMode(int reportType, int reportMode);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _DEBUG */
 
 #define _CrtDoForAllClientObjects(f,c)  ((void)0)
diff --git a/include/msvcrt/signal.h b/include/msvcrt/signal.h
index 5a77a0067fe..2155bb4b46b 100644
--- a/include/msvcrt/signal.h
+++ b/include/msvcrt/signal.h
@@ -33,6 +33,10 @@
 
 #define NSIG     (SIGABRT + 1)
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef void (*__sighandler_t)(int);
 
 #define SIG_DFL ((__sighandler_t)0)
@@ -42,4 +46,8 @@ typedef void (*__sighandler_t)(int);
 __sighandler_t signal(int sig, __sighandler_t func);
 int raise(int sig);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _WINE_SIGNAL_H */