diff --git a/Makefile b/Makefile
index c7b05a9a..a9ae2e7a 100644
--- a/Makefile
+++ b/Makefile
@@ -43,6 +43,13 @@ LDFLAGS  =
 CFLAGS   += -D_XOPEN_SOURCE=600
 CXXFLAGS += -D_XOPEN_SOURCE=600
 
+# RLIMIT_MEMLOCK came in BSD, is not specified in POSIX.1,
+# and on macOS its availability depends on enabling Darwin extensions
+ifeq ($(UNAME_S),Darwin)
+	CFLAGS   += -D_DARWIN_C_SOURCE
+	CXXFLAGS += -D_DARWIN_C_SOURCE
+endif
+
 # OS specific
 # TODO: support Windows
 ifeq ($(UNAME_S),Linux)
diff --git a/examples/talk-llama/llama-util.h b/examples/talk-llama/llama-util.h
index 3cac9f68..4d510063 100644
--- a/examples/talk-llama/llama-util.h
+++ b/examples/talk-llama/llama-util.h
@@ -186,8 +186,8 @@ struct llama_mmap {
 
         if (prefetch > 0) {
             // Advise the kernel to preload the mapped memory
-            if (madvise(addr, std::min(file->size, prefetch), MADV_WILLNEED)) {
-                fprintf(stderr, "warning: madvise(.., MADV_WILLNEED) failed: %s\n",
+            if (posix_madvise(addr, std::min(file->size, prefetch), POSIX_MADV_WILLNEED)) {
+                fprintf(stderr, "warning: posix_madvise(.., POSIX_MADV_WILLNEED) failed: %s\n",
                         strerror(errno));
             }
         }