diff --git a/src/pal/pal_apple.h b/src/pal/pal_apple.h
index eabc489..9e456d5 100644
--- a/src/pal/pal_apple.h
+++ b/src/pal/pal_apple.h
@@ -8,7 +8,7 @@
 #  include <strings.h>
 #  include <sys/mman.h>
 
-int puts(const char* str);
+extern "C" int puts(const char* str);
 
 namespace snmalloc
 {
diff --git a/src/pal/pal_linux.h b/src/pal/pal_linux.h
index b1af854..fa83a45 100644
--- a/src/pal/pal_linux.h
+++ b/src/pal/pal_linux.h
@@ -7,7 +7,7 @@
 #  include <string.h>
 #  include <sys/mman.h>
 
-int puts(const char* str);
+extern "C" int puts(const char* str);
 
 namespace snmalloc
 {