diff --git a/Library/MemLogLibDefault/MemLogLib.c b/Library/MemLogLibDefault/MemLogLib.c
index 3da0a95af..4596a0c9d 100644
--- a/Library/MemLogLibDefault/MemLogLib.c
+++ b/Library/MemLogLibDefault/MemLogLib.c
@@ -469,7 +469,7 @@ static void transmitS8Printf(const char* buf, unsigned int nbchar, void* context
   mMemLog->Cursor += nbchar;
 }
 
-const char* printf_lite_get_timestamp()
+const char* printf_lite_get_timestamp(void)
 {
   UINT64    dTStartSec;
   UINT64    dTStartMs;
diff --git a/MdePkg/Include/Library/DebugLib.h b/MdePkg/Include/Library/DebugLib.h
index 4eaf08e84..2d8a67609 100644
--- a/MdePkg/Include/Library/DebugLib.h
+++ b/MdePkg/Include/Library/DebugLib.h
@@ -551,7 +551,7 @@ DebugPrintLevelEnabled (
   are not included in a module.
 
 **/
-#define DEBUG_CODE_END()    __DebugCodeLocal = 0; __DebugCodeLocal++; } } while (FALSE)
+#define DEBUG_CODE_END()    __DebugCodeLocal = 0; __DebugCodeLocal++; (void)__DebugCodeLocal; } } while (FALSE)
 
 
 /**
diff --git a/MdePkg/Include/Library/PerformanceLib.h b/MdePkg/Include/Library/PerformanceLib.h
index 813c4f5d1..7a051dc98 100644
--- a/MdePkg/Include/Library/PerformanceLib.h
+++ b/MdePkg/Include/Library/PerformanceLib.h
@@ -745,7 +745,7 @@ LogPerformanceMeasurement (
   Otherwise, the source lines between PERF_CODE_BEGIN() and PERF_CODE_END() are not included in a module.
 
 **/
-#define PERF_CODE_END()    __PerformanceCodeLocal = 0; __PerformanceCodeLocal++; } } while (FALSE)
+#define PERF_CODE_END()    __PerformanceCodeLocal = 0; __PerformanceCodeLocal++; (void)__PerformanceCodeLocal; } } while (FALSE)
 
 /**
   Macro that declares a section of performance measurement source code.
diff --git a/Protocols/SMCHelper/SMCHelper.c b/Protocols/SMCHelper/SMCHelper.c
index c698e78b2..4dcab8ba1 100644
--- a/Protocols/SMCHelper/SMCHelper.c
+++ b/Protocols/SMCHelper/SMCHelper.c
@@ -337,7 +337,6 @@ SmcGetKeyInfoImpl (IN  APPLE_SMC_IO_PROTOCOL  *This,
                    OUT SMC_KEY_ATTRIBUTES     *Attributes
                    )
 {
-  UINT32 Num = 0;
   SMC_STACK *TmpStack = SmcStack;
   if (!Size || !Type || !Attributes) {
     return EFI_INVALID_PARAMETER;
@@ -349,7 +348,6 @@ SmcGetKeyInfoImpl (IN  APPLE_SMC_IO_PROTOCOL  *This,
       *Attributes = TmpStack->Attributes;
       return EFI_SUCCESS;
     }
-    Num++;
     TmpStack = TmpStack->Next;
   }
   return EFI_NOT_FOUND;  
diff --git a/rEFIt_UEFI/Platform/smbios.cpp b/rEFIt_UEFI/Platform/smbios.cpp
index baef145d7..87ab8ef96 100755
--- a/rEFIt_UEFI/Platform/smbios.cpp
+++ b/rEFIt_UEFI/Platform/smbios.cpp
@@ -1454,7 +1454,10 @@ void PatchTableType17(const SmbiosInjectedSettings& smbiosSettings, XArray<UINT1
   XArray<UINT16>& mHandle17 = *mHandle17Ptr;
   XString8   deviceLocator;
   XString8   bankLocator;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wvla-extension"
   UINT8   channelMap[mMemory17.size()]; // mMemory17.size() == SlotCounts
+#pragma clang diagnostic pop
   UINT8   expectedCount = 0;
   UINT8   channels = 2;
   XBool insertingEmpty = true;
diff --git a/rEFIt_UEFI/cpp_unit_test/printlib-test.cpp b/rEFIt_UEFI/cpp_unit_test/printlib-test.cpp
index a7af8317d..18f6bd724 100644
--- a/rEFIt_UEFI/cpp_unit_test/printlib-test.cpp
+++ b/rEFIt_UEFI/cpp_unit_test/printlib-test.cpp
@@ -171,6 +171,9 @@ int printlib_tests(void)
     loggf(F("SIZE_T_MAX=%zu\n"), SIZE_T_MAX);
     loggf(F("\n"));
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat"
+
     loggf(F("PRId16=%a\n"), PRId16);
     loggf(F("PRIu16=%a\n"), PRIu16);
     loggf(F("PRId32=%a\n"), PRId32);
@@ -179,6 +182,9 @@ int printlib_tests(void)
     loggf(F("PRIu32=%a\n"), PRIu32);
     loggf(F("PRId64=%a\n"), PRId64);
     loggf(F("PRIu64=%a\n"), PRIu64);
+
+#pragma GCC diagnostic pop
+
     loggf(F("\n"));
 #endif