diff --git a/objectivec/GPBUtilities_PackagePrivate.h b/objectivec/GPBUtilities_PackagePrivate.h
index f04ed8316b22..c9884cdbc0f0 100644
--- a/objectivec/GPBUtilities_PackagePrivate.h
+++ b/objectivec/GPBUtilities_PackagePrivate.h
@@ -58,7 +58,7 @@ CF_EXTERN_C_BEGIN
 // These two are used to inject a runtime check for version mismatch into the
 // generated sources to make sure they are linked with a supporting runtime.
 void GPBCheckRuntimeVersionSupport(int32_t objcRuntimeVersion);
-GPB_INLINE void GPB_DEBUG_CHECK_RUNTIME_VERSIONS() {
+GPB_INLINE void GPB_DEBUG_CHECK_RUNTIME_VERSIONS(void) {
   // NOTE: By being inline here, this captures the value from the library's
   // headers at the time the generated code was compiled.
 #if defined(DEBUG) && DEBUG
@@ -69,7 +69,7 @@ GPB_INLINE void GPB_DEBUG_CHECK_RUNTIME_VERSIONS() {
 // Legacy version of the checks, remove when GOOGLE_PROTOBUF_OBJC_GEN_VERSION
 // goes away (see more info in GPBBootstrap.h).
 void GPBCheckRuntimeVersionInternal(int32_t version);
-GPB_INLINE void GPBDebugCheckRuntimeVersion() {
+GPB_INLINE void GPBDebugCheckRuntimeVersion(void) {
 #if defined(DEBUG) && DEBUG
   GPBCheckRuntimeVersionInternal(GOOGLE_PROTOBUF_OBJC_GEN_VERSION);
 #endif
diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h
index 757d02c0cf5b..d47404e7c6f5 100644
--- a/src/google/protobuf/arena.h
+++ b/src/google/protobuf/arena.h
@@ -426,7 +426,7 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
     }
 
     template <typename U>
-    static Arena* GetOwningArena(Rank1, const U* p) {
+    static Arena* GetOwningArena(Rank1, const U*) {
       return nullptr;
     }
 
@@ -456,7 +456,7 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
     }
 
     template <typename U>
-    static Arena* GetArenaForAllocation(Rank2, const U* p) {
+    static Arena* GetArenaForAllocation(Rank2, const U*) {
       return nullptr;
     }