diff --git a/src/options.c b/src/options.c
index a93ea89e..4c76ae41 100644
--- a/src/options.c
+++ b/src/options.c
@@ -9,7 +9,8 @@ terms of the MIT license. A copy of the license can be found in the file
 #include "mimalloc-atomic.h"
 #include "prim/prim.h"  // mi_prim_out_stderr
 
-#include <stdio.h>
+#include <stdio.h>      // FILE
+#include <stdlib.h>     // abort
 #include <stdarg.h>
 
 
diff --git a/src/prim/prim-unix.c b/src/prim/prim-unix.c
index 495b274e..ce24c24a 100644
--- a/src/prim/prim-unix.c
+++ b/src/prim/prim-unix.c
@@ -504,7 +504,13 @@ mi_msecs_t _mi_prim_clock_now(void) {
 
 // low resolution timer
 mi_msecs_t _mi_prim_clock_now(void) {
-  return ((mi_msecs_t)clock() / ((mi_msecs_t)CLOCKS_PER_SEC / 1000));
+  #if !defined(CLOCKS_PER_SEC) || (CLOCKS_PER_SEC == 1000) || (CLOCKS_PER_SEC == 0)
+  return (mi_msecs_t)clock();  
+  #elif (CLOCKS_PER_SEC < 1000)
+  return (mi_msecs_t)clock() * (1000 / (mi_msecs_t)CLOCKS_PER_SEC);  
+  #else
+  return (mi_msecs_t)clock() / ((mi_msecs_t)CLOCKS_PER_SEC / 1000);
+  #endif
 }
 
 #endif
diff --git a/src/prim/prim-wasi.c b/src/prim/prim-wasi.c
index 7de491e4..c37b0847 100644
--- a/src/prim/prim-wasi.c
+++ b/src/prim/prim-wasi.c
@@ -110,7 +110,7 @@ static void* mi_prim_mem_grow(size_t size, size_t try_alignment) {
 
 // Note: the `try_alignment` is just a hint and the returned pointer is not guaranteed to be aligned.
 void* _mi_prim_alloc(size_t size, size_t try_alignment, bool commit, bool allow_large, bool* is_large) {
-  MI_UNUSED(allow_large);
+  MI_UNUSED(allow_large); MI_UNUSED(commit);
   *is_large = false;
   return mi_prim_mem_grow(size, try_alignment);
 }
@@ -176,7 +176,13 @@ mi_msecs_t _mi_prim_clock_now(void) {
 
 // low resolution timer
 mi_msecs_t _mi_prim_clock_now(void) {
-  return ((mi_msecs_t)clock() / ((mi_msecs_t)CLOCKS_PER_SEC / 1000));
+  #if !defined(CLOCKS_PER_SEC) || (CLOCKS_PER_SEC == 1000) || (CLOCKS_PER_SEC == 0)
+  return (mi_msecs_t)clock();  
+  #elif (CLOCKS_PER_SEC < 1000)
+  return (mi_msecs_t)clock() * (1000 / (mi_msecs_t)CLOCKS_PER_SEC);  
+  #else
+  return (mi_msecs_t)clock() / ((mi_msecs_t)CLOCKS_PER_SEC / 1000);
+  #endif
 }
 
 #endif
diff --git a/src/prim/prim-windows.c b/src/prim/prim-windows.c
index 97b1936f..f6f1a9db 100644
--- a/src/prim/prim-windows.c
+++ b/src/prim/prim-windows.c
@@ -408,6 +408,10 @@ mi_msecs_t _mi_prim_clock_now(void) {
 }
 
 
+//----------------------------------------------------------------
+// Process Info
+//----------------------------------------------------------------
+
 #include <windows.h>
 #include <psapi.h>
 
@@ -470,7 +474,7 @@ void _mi_prim_out_stderr( const char* msg )
       hcon = GetStdHandle(STD_ERROR_HANDLE);
       hconIsConsole = ((hcon != INVALID_HANDLE_VALUE) && GetConsoleScreenBufferInfo(hcon, &sbi));
     }
-    const size_t len = strlen(msg);
+    const size_t len = _mi_strlen(msg);
     if (len > 0 && len < UINT32_MAX) {
       DWORD written = 0;
       if (hconIsConsole) {
@@ -501,4 +505,4 @@ bool _mi_prim_getenv(const char* name, char* result, size_t result_size) {
   result[0] = 0;
   size_t len = GetEnvironmentVariableA(name, result, (DWORD)result_size);
   return (len > 0 && len < result_size);
-}
\ No newline at end of file
+}
diff --git a/src/prim/prim.h b/src/prim/prim.h
index 734d02bf..2cbbc85c 100644
--- a/src/prim/prim.h
+++ b/src/prim/prim.h
@@ -9,9 +9,9 @@ terms of the MIT license. A copy of the license can be found in the file
 #define MIMALLOC_PRIM_H
 
 // note: on all primitive functions, we always get:
-// addr != NULL and page aligned
-// size > 0     and page aligned
-// 
+//  addr != NULL and page aligned
+//  size > 0     and page aligned
+
 
 // OS memory configuration
 typedef struct mi_os_mem_config_s {
@@ -26,12 +26,10 @@ typedef struct mi_os_mem_config_s {
 void  _mi_prim_mem_init( mi_os_mem_config_t* config );
 
 // Free OS memory
-// pre: addr != NULL, size > 0
 void  _mi_prim_free(void* addr, size_t size );
   
-// Allocate OS memory.
+// Allocate OS memory. Return NULL on error.
 // The `try_alignment` is just a hint and the returned pointer does not have to be aligned.
-// return NULL on error.
 // pre: !commit => !allow_large
 //      try_alignment >= _mi_os_page_size() and a power of 2
 void* _mi_prim_alloc(size_t size, size_t try_alignment, bool commit, bool allow_large, bool* is_large);
@@ -58,23 +56,20 @@ size_t _mi_prim_numa_node(void);
 // Return the number of logical NUMA nodes
 size_t _mi_prim_numa_node_count(void);
 
-// High resolution clock
+// Clock ticks
 mi_msecs_t _mi_prim_clock_now(void);
 
-// Return process information
+// Return process information (only for statistics)
 void  _mi_prim_process_info(mi_msecs_t* utime, mi_msecs_t* stime, 
                              size_t* current_rss, size_t* peak_rss, 
                              size_t* current_commit, size_t* peak_commit, size_t* page_faults);
 
-// Default stderr output. 
-// msg != NULL && strlen(msg) > 0
+// Default stderr output. (only for warnings etc. with verbose enabled)
+// msg != NULL && _mi_strlen(msg) > 0
 void  _mi_prim_out_stderr( const char* msg );
 
-// Get an environment variable.
+// Get an environment variable. (only for options)
 // name != NULL, result != NULL, result_size >= 64
 bool _mi_prim_getenv(const char* name, char* result, size_t result_size);
 
-
 #endif  // MIMALLOC_PRIM_H
-
-