diff --git a/Source/cmListFileLexer.c b/Source/cmListFileLexer.c
index 31faca1bca..56559f67a3 100644
--- a/Source/cmListFileLexer.c
+++ b/Source/cmListFileLexer.c
@@ -2518,7 +2518,7 @@ static void cmListFileLexerDestroy(cmListFileLexer* lexer)
 }
 
 /*--------------------------------------------------------------------------*/
-cmListFileLexer* cmListFileLexer_New()
+cmListFileLexer* cmListFileLexer_New(void)
 {
   cmListFileLexer* lexer = (cmListFileLexer*)malloc(sizeof(cmListFileLexer));
   if (!lexer) {
diff --git a/Source/cmListFileLexer.h b/Source/cmListFileLexer.h
index dfbad5ee1b..c9fb6da1d6 100644
--- a/Source/cmListFileLexer.h
+++ b/Source/cmListFileLexer.h
@@ -46,7 +46,7 @@ typedef struct cmListFileLexer_s cmListFileLexer;
 extern "C" {
 #endif
 
-cmListFileLexer* cmListFileLexer_New();
+cmListFileLexer* cmListFileLexer_New(void);
 int cmListFileLexer_SetFileName(cmListFileLexer*, const char*,
                                 cmListFileLexer_BOM* bom);
 int cmListFileLexer_SetString(cmListFileLexer*, const char*);
diff --git a/Source/cmListFileLexer.in.l b/Source/cmListFileLexer.in.l
index 4b389b9252..dd649234fa 100644
--- a/Source/cmListFileLexer.in.l
+++ b/Source/cmListFileLexer.in.l
@@ -398,7 +398,7 @@ static void cmListFileLexerDestroy(cmListFileLexer* lexer)
 }
 
 /*--------------------------------------------------------------------------*/
-cmListFileLexer* cmListFileLexer_New()
+cmListFileLexer* cmListFileLexer_New(void)
 {
   cmListFileLexer* lexer = (cmListFileLexer*)malloc(sizeof(cmListFileLexer));
   if (!lexer) {