diff --git a/Sources/HTMLNode.m b/Sources/HTMLNode.m
index be9bb9e..d948ff9 100644
--- a/Sources/HTMLNode.m
+++ b/Sources/HTMLNode.m
@@ -589,7 +589,7 @@ NS_INLINE void CheckInvalidCombination(HTMLNode *parent, HTMLNode *node, NSStrin
 
 	CheckInvalidCombination(self, node, ValidationNodePreInsertion);
 
-	void (^ hierarchyError)() = ^{
+	void (^ hierarchyError)(void) = ^{
 		[NSException raise:HTMLKitHierarchyRequestError
 					format:@"%@: Hierarchy Request Error, inserting (%@) into (%@). The operation would yield an incorrect node tree.",
 		 ValidationNodePreInsertion, self, node];
@@ -639,7 +639,7 @@ NS_INLINE void CheckInvalidCombination(HTMLNode *parent, HTMLNode *node, NSStrin
 
 	CheckInvalidCombination(self, node, ValidationNodeReplacement);
 
-	void (^ hierarchyError)() = ^{
+	void (^ hierarchyError)(void) = ^{
 		[NSException raise:HTMLKitHierarchyRequestError
 					format:@"%@: Hierarchy Request Error. The operation would yield an incorrect node tree.",
 		 ValidationNodeReplacement];
diff --git a/Sources/HTMLParser.m b/Sources/HTMLParser.m
index 2485650..9926fea 100644
--- a/Sources/HTMLParser.m
+++ b/Sources/HTMLParser.m
@@ -2530,7 +2530,7 @@
 			return;
 		case HTMLTokenTypeStartTag:
 		{
-			void (^ anythingElse)() = ^ {
+			void (^ anythingElse)(void) = ^ {
 				if (self.adjustedCurrentNode.htmlNamespace == HTMLNamespaceMathML) {
 					AdjustMathMLAttributes(token.asTagToken);
 				}
@@ -2545,7 +2545,7 @@
 				}
 			};
 
-			void (^ matchedCase)() = ^ {
+			void (^ matchedCase)(void) = ^ {
 				[self emitParseError:@"Unexpected start tag <%@> in foreign content", token.asTagToken.tagName];
 				if (_fragmentParsingAlgorithm) {
 					anythingElse();
diff --git a/Sources/include/CSSSelectors.h b/Sources/include/CSSSelectors.h
index c877fa2..bd8acd9 100644
--- a/Sources/include/CSSSelectors.h
+++ b/Sources/include/CSSSelectors.h
@@ -26,7 +26,7 @@ NS_ASSUME_NONNULL_BEGIN
 
  @return The universal CSS selector.
  */
-extern CSSSelector * universalSelector();
+extern CSSSelector * universalSelector(void);
 
 /**
  CSS type selector, e.g. 'div', 'p', ...etc.
@@ -125,7 +125,7 @@ extern CSSSelector * nthLastOfTypeSelector(CSSNthExpression expression);
 
  @return Odd-Child selector.
  */
-extern CSSSelector * oddSelector();
+extern CSSSelector * oddSelector(void);
 
 /**
  CSS even-child selector: ':nth-child(even)'
@@ -134,49 +134,49 @@ extern CSSSelector * oddSelector();
 
  @return Even-Child selector.
  */
-extern CSSSelector * evenSlector();
+extern CSSSelector * evenSlector(void);
 
 /**
  CSS first-child selector: ':nth-child(1)'
 
  @return First-Child selector.
  */
-extern CSSSelector * firstChildSelector();
+extern CSSSelector * firstChildSelector(void);
 
 /**
  CSS first-child selector: ':nth-last-child(1)'
 
  @return First-Child selector.
  */
-extern CSSSelector * lastChildSelector();
+extern CSSSelector * lastChildSelector(void);
 
 /**
  CSS first-of-type selector: ':nth-first-of-type(1)'
 
  @return First-Of-Type selector.
  */
-extern CSSSelector * firstOfTypeSelector();
+extern CSSSelector * firstOfTypeSelector(void);
 
 /**
  CSS last-of-type selector: ':nth-last-of-type(1)'
 
  @return Last-Of-Type selector.
  */
-extern CSSSelector * lastOfTypeSelector();
+extern CSSSelector * lastOfTypeSelector(void);
 
 /**
  CSS only-child selector: ':first-child:last-child'
 
  @return Only-Child selector.
  */
-extern CSSSelector * onlyChildSelector();
+extern CSSSelector * onlyChildSelector(void);
 
 /**
  CSS only-of-type selector: ':first-of-type:last-of-type'
 
  @return Only-Of-Type selector.
  */
-extern CSSSelector * onlyOfTypeSelector();
+extern CSSSelector * onlyOfTypeSelector(void);
 
 #pragma mark - Combinators
 
diff --git a/Sources/include/CSSStructuralPseudoSelectors.h b/Sources/include/CSSStructuralPseudoSelectors.h
index 39ac7d2..1b75b1a 100644
--- a/Sources/include/CSSStructuralPseudoSelectors.h
+++ b/Sources/include/CSSStructuralPseudoSelectors.h
@@ -15,102 +15,102 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  @return Root element selector: ':root'
  */
-extern CSSSelector * rootSelector();
+extern CSSSelector * rootSelector(void);
 
 /**
  @return Empy element selector: ':empty'
  */
-extern CSSSelector * emptySelector();
+extern CSSSelector * emptySelector(void);
 
 /**
  @return A parent element selector: ':parent'
  */
-extern CSSSelector * parentSelector();
+extern CSSSelector * parentSelector(void);
 
 /**
  @return A button element selector: ':button'
  */
-extern CSSSelector * buttonSelector();
+extern CSSSelector * buttonSelector(void);
 
 /**
  @return A checkbox element selector: ':checkbox'
  */
-extern CSSSelector * checkboxSelector();
+extern CSSSelector * checkboxSelector(void);
 
 /**
  @return A file element selector: ':file'
  */
-extern CSSSelector * fileSelector();
+extern CSSSelector * fileSelector(void);
 
 /**
  @return A header element selector: ':header'
  */
-extern CSSSelector * headerSelector();
+extern CSSSelector * headerSelector(void);
 
 /**
  @return An image element selector: ':image'
  */
-extern CSSSelector * imageSelector();
+extern CSSSelector * imageSelector(void);
 
 /**
  @return A parent element selector: ':parent'
  */
-extern CSSSelector * inputSelector();
+extern CSSSelector * inputSelector(void);
 
 /**
  @return A link element selector: ':link'
  */
-extern CSSSelector * linkSelector();
+extern CSSSelector * linkSelector(void);
 
 /**
  @return A password element selector: ':password'
  */
-extern CSSSelector * passwordSelector();
+extern CSSSelector * passwordSelector(void);
 
 /**
  @return A radio element selector: ':radio'
  */
-extern CSSSelector * radioSelector();
+extern CSSSelector * radioSelector(void);
 
 /**
  @return A reset element selector: ':reset'
  */
-extern CSSSelector * resetSelector();
+extern CSSSelector * resetSelector(void);
 
 /**
  @return A submit element selector: ':submit'
  */
-extern CSSSelector * submitSelector();
+extern CSSSelector * submitSelector(void);
 
 /**
  @return A text element selector: ':text'
  */
-extern CSSSelector * textSelector();
+extern CSSSelector * textSelector(void);
 
 /**
  @return An enabled element selector: ':enabled'
  */
-extern CSSSelector * enabledSelector();
+extern CSSSelector * enabledSelector(void);
 
 /**
  @return A disabled element selector: ':disabled'
  */
-extern CSSSelector * disabledSelector();
+extern CSSSelector * disabledSelector(void);
 
 /**
  @return A checked element selector: ':checked'
  */
-extern CSSSelector * checkedSelector();
+extern CSSSelector * checkedSelector(void);
 
 /**
  @return An optional element selector: ':optional'
  */
-extern CSSSelector * optionalSelector();
+extern CSSSelector * optionalSelector(void);
 
 /**
  @return A required element selector: ':required'
  */
-extern CSSSelector * requiredSelector();
+extern CSSSelector * requiredSelector(void);
 
 /**
  Less-than selector, e.g. 'lt(2)'
diff --git a/Tests/HTMLKitTests/HTML5LibTreeConstructionTest.m b/Tests/HTMLKitTests/HTML5LibTreeConstructionTest.m
index e46a5c0..3b08d2c 100644
--- a/Tests/HTMLKitTests/HTML5LibTreeConstructionTest.m
+++ b/Tests/HTMLKitTests/HTML5LibTreeConstructionTest.m
@@ -46,7 +46,7 @@ static NSString * const TreeConstruction = @"tree-construction";
 	NSMutableArray *tests = [NSMutableArray array];
 
 	NSScanner *scanner = [NSScanner scannerWithString:contents];
-	NSString * (^ nextTest)() = ^ NSString * () {
+	NSString * (^ nextTest)(void) = ^ NSString * () {
 		NSString *str;
 		[scanner scanUpToString:@"\n\n#data" intoString:&str];
 		return str;
diff --git a/Tests/HTMLKitTests/HTMLMutationAlgorithmsTests.m b/Tests/HTMLKitTests/HTMLMutationAlgorithmsTests.m
index 421065b..127e7f4 100644
--- a/Tests/HTMLKitTests/HTMLMutationAlgorithmsTests.m
+++ b/Tests/HTMLKitTests/HTMLMutationAlgorithmsTests.m
@@ -157,7 +157,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLDocument *document = [HTMLDocument new];
 	HTMLDocumentFragment *fragment = [[HTMLDocumentFragment alloc] initWithDocument:document];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[fragment removeAllChildNodes];
 		[document removeAllChildNodes];
 	};
@@ -213,7 +213,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLDocument *document = [HTMLDocument new];
 	HTMLElement *element = [HTMLElement new];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[element removeAllChildNodes];
 		[document removeAllChildNodes];
 	};
@@ -247,7 +247,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLDocument *document = [HTMLDocument new];
 	HTMLDocumentType *doctype = [HTMLDocumentType new];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[document removeAllChildNodes];
 	};
 
@@ -280,7 +280,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLComment *child = [HTMLComment new];
 	HTMLDocumentFragment *replacement = [[HTMLDocumentFragment alloc] initWithDocument:document];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[replacement removeAllChildNodes];
 		[document removeAllChildNodes];
 		[document appendNode:child];
@@ -326,7 +326,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLComment *child = [HTMLComment new];
 	HTMLElement *replacement = [HTMLElement new];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[replacement removeAllChildNodes];
 		[document removeAllChildNodes];
 		[document appendNode:child];
@@ -353,7 +353,7 @@ extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 	HTMLComment *child = [HTMLComment new];
 	HTMLDocumentType *replacement = [HTMLDocumentType new];
 
-	void (^ reset)() = ^ {
+	void (^ reset)(void) = ^ {
 		[replacement removeAllChildNodes];
 		[document removeAllChildNodes];
 		[document appendNode:child];