diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9ad9dbce9..4bcdf44d9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -383,14 +383,14 @@ endif()
 ## Compiler standard version
 
 if(CMAKE_VERSION VERSION_LESS "3.1")
-    if(CMAKE_C_COMPILER_ID STREQUAL "GNU" OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99")
+    if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu11")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++17")
     elseif(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /std:c++17")
     endif()
 else()
-    set(CMAKE_C_STANDARD 99)
+    set(CMAKE_C_STANDARD 11)
     set(CMAKE_C_STANDARD_REQUIRED ON)
     set(CMAKE_CXX_STANDARD 17)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
diff --git a/libtransmission/tr-macros.h b/libtransmission/tr-macros.h
index 9ba0f4621..1d0c96ca6 100644
--- a/libtransmission/tr-macros.h
+++ b/libtransmission/tr-macros.h
@@ -139,15 +139,12 @@
  * @def TR_STATIC_ASSERT
  * @brief This helper allows to perform static checks at compile time
  */
-#if defined(static_assert)
+#if defined(__cplusplus) || defined(static_assert)
 #define TR_STATIC_ASSERT static_assert
-#elif __has_feature(c_static_assert) || __has_extension(c_static_assert)
+#elif __has_feature(c_static_assert) || __has_extension(c_static_assert) || TR_GNUC_CHECK_VERSION(4, 6)
 #define TR_STATIC_ASSERT _Static_assert
 #else
-#define TR_STATIC_ASSERT(x, msg) \
-    { \
-        typedef char __tr_static_check__ [(x) ? 1 : -1] UNUSED; \
-    }
+#define TR_STATIC_ASSERT(x, msg) (void)(x)
 #endif
 
 /* Sometimes the system defines MAX/MIN, sometimes not.