diff --git a/src/os/unix/ngx_atomic.h b/src/os/unix/ngx_atomic.h
index 7f74038..c5197e5 100644
--- a/src/os/unix/ngx_atomic.h
+++ b/src/os/unix/ngx_atomic.h
@@ -8,6 +8,8 @@
 
 #if ( __i386__ || __amd64__ )
 
+#define NGX_HAVE_ATOMIC_OPS  1
+
 typedef volatile uint32_t  ngx_atomic_t;
 
 #if (NGX_SMP)
@@ -33,6 +35,8 @@
 }
 
 
+#if 0
+
 static ngx_inline uint32_t ngx_atomic_dec(ngx_atomic_t *value)
 {
     uint32_t  old;
@@ -48,6 +52,8 @@
     return old;
 }
 
+#endif
+
 
 static ngx_inline uint32_t ngx_atomic_cmp_set(ngx_atomic_t *lock,
                                               ngx_atomic_t old,
@@ -70,6 +76,8 @@
 
 #elif ( __sparc__ )
 
+#define NGX_HAVE_ATOMIC_OPS  1
+
 typedef volatile uint32_t  ngx_atomic_t;
 
 
@@ -99,11 +107,6 @@
 }
 
 
-/* STUB */
-#define ngx_atomic_dec(x)   (*(x))--;
-/**/
-
-
 static ngx_inline uint32_t ngx_atomic_cmp_set(ngx_atomic_t *lock,
                                               ngx_atomic_t old,
                                               ngx_atomic_t set)
@@ -121,13 +124,18 @@
 
 #else
 
+#define NGX_HAVE_ATOMIC_OPS  0
+
 typedef volatile uint32_t  ngx_atomic_t;
 
-/* STUB */
-#define ngx_atomic_inc(x)   ++(*(x));
-#define ngx_atomic_dec(x)   --(*(x));
-#define ngx_atomic_cmp_set(lock, old, set)   1
-/**/
+#define ngx_atomic_inc(x)  ++(*(x));
+
+static ngx_inline uint32_t ngx_atomic_cmp_set(ngx_atomic_t *lock,
+                                              ngx_atomic_t old,
+                                              ngx_atomic_t set)
+{
+     return 1;
+}
 
 #endif
 
diff --git a/src/os/win32/ngx_atomic.h b/src/os/win32/ngx_atomic.h
index fcc3ff1..9d75fab 100644
--- a/src/os/win32/ngx_atomic.h
+++ b/src/os/win32/ngx_atomic.h
@@ -6,17 +6,23 @@
 #include <ngx_core.h>
 
 
+#define NGX_HAVE_ATOMIC_OPS   1
+
+
 #define ngx_atomic_inc(p)       InterlockedIncrement((long *) p)
-#define ngx_atomic_dec(p)       InterlockedDecrement((long *) p)
 
 
 #if defined( __WATCOMC__ ) || defined( __BORLANDC__ )
 
+/* the new SDK headers */
+
 #define ngx_atomic_cmp_set(lock, old, set)                                    \
      (InterlockedCompareExchange((long *) lock, set, old) == old)
 
 #else
 
+/* the old MS VC6.0SP2 SDK headers */
+
 #define ngx_atomic_cmp_set(lock, old, set)                                    \
      (InterlockedCompareExchange((void **) lock, (void *) set, (void *) old)  \
       == (void *) old)