diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index 130c50b85c..bf4feaec2d 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -42,7 +42,6 @@
 #include "nvim/ui_client.h"
 #include "nvim/ui_compositor.h"
 #include "nvim/usercmd.h"
-#include "nvim/vim_defs.h"
 
 #ifdef UNIT_TESTING
 # define malloc(size) mem_malloc(size)
@@ -65,7 +64,7 @@ bool entered_free_all_mem = false;
 
 /// Try to free memory. Used when trying to recover from out of memory errors.
 /// @see {xmalloc}
-void try_to_free_memory(void)
+static void try_to_free_memory(void)
 {
   static bool trying_to_free = false;
   // avoid recursive calls
@@ -84,6 +83,24 @@ void try_to_free_memory(void)
   trying_to_free = false;
 }
 
+/// Avoid repeating the error message many times (they take 1 second each).
+/// `did_outofmem_msg` is reset when a character is read.
+static void do_outofmem_msg(size_t size)
+{
+  if (did_outofmem_msg) {
+    return;
+  }
+
+  // Don't hide this message
+  emsg_silent = 0;
+
+  // Must come first to avoid coming back here when printing the error
+  // message fails, e.g. when setting v:errmsg.
+  did_outofmem_msg = true;
+
+  semsg(_("E342: Out of memory!  (allocating %" PRIu64 " bytes)"), (uint64_t)size);
+}
+
 /// malloc() wrapper
 ///
 /// try_malloc() is a malloc() wrapper that tries to free some memory before
@@ -540,24 +557,6 @@ bool strnequal(const char *a, const char *b, size_t n)
   return (a == NULL && b == NULL) || (a && b && strncmp(a, b, n) == 0);
 }
 
-// Avoid repeating the error message many times (they take 1 second each).
-// Did_outofmem_msg is reset when a character is read.
-void do_outofmem_msg(size_t size)
-{
-  if (did_outofmem_msg) {
-    return;
-  }
-
-  // Don't hide this message
-  emsg_silent = 0;
-
-  // Must come first to avoid coming back here when printing the error
-  // message fails, e.g. when setting v:errmsg.
-  did_outofmem_msg = true;
-
-  semsg(_("E342: Out of memory!  (allocating %" PRIu64 " bytes)"), (uint64_t)size);
-}
-
 /// Writes time_t to "buf[8]".
 void time_to_bytes(time_t time_, uint8_t buf[8])
 {
diff --git a/src/nvim/memory.h b/src/nvim/memory.h
index 71acb22e7a..171b8ede4f 100644
--- a/src/nvim/memory.h
+++ b/src/nvim/memory.h
@@ -21,10 +21,6 @@ typedef void *(*MemCalloc)(size_t, size_t);
 /// `realloc()` function signature
 typedef void *(*MemRealloc)(void *, size_t);
 
-typedef void *(*MergeSortGetFunc)(void *);
-typedef void (*MergeSortSetFunc)(void *, void *);
-typedef int (*MergeSortCompareFunc)(const void *, const void *);
-
 #ifdef UNIT_TESTING
 /// When unit testing: pointer to the `malloc()` function, may be altered
 extern MemMalloc mem_malloc;
@@ -44,6 +40,10 @@ extern MemRealloc mem_realloc;
 extern bool entered_free_all_mem;
 #endif
 
+typedef void *(*MergeSortGetFunc)(void *);
+typedef void (*MergeSortSetFunc)(void *, void *);
+typedef int (*MergeSortCompareFunc)(const void *, const void *);
+
 EXTERN size_t arena_alloc_count INIT( = 0);
 
 #define kv_fixsize_arena(a, v, s) \