diff --git a/coregrind/m_aspacemgr/priv_aspacemgr.h b/coregrind/m_aspacemgr/priv_aspacemgr.h
index 730e53694..34605a02c 100644
--- a/coregrind/m_aspacemgr/priv_aspacemgr.h
+++ b/coregrind/m_aspacemgr/priv_aspacemgr.h
@@ -77,7 +77,7 @@ extern void   ML_(am_assert_fail) ( const HChar* expr,
                                     const HChar* fn );
 
 #define aspacem_assert(expr)                              \
-  ((void) ((expr) ? 0 :                                   \
+  ((void) (LIKELY(expr) ? 0 :                             \
            (ML_(am_assert_fail)(#expr,                    \
                                 __FILE__, __LINE__,       \
                                 __PRETTY_FUNCTION__))))
diff --git a/coregrind/m_libcbase.c b/coregrind/m_libcbase.c
index 97af7c7c2..a84eb34aa 100644
--- a/coregrind/m_libcbase.c
+++ b/coregrind/m_libcbase.c
@@ -35,11 +35,11 @@
 
 
 /* ---------------------------------------------------------------------
-   Assert machinery for use in this file. VG_(assert) cannot be called
+   Assert machinery for use in this file. vg_assert cannot be called
    here due to cyclic dependencies.
    ------------------------------------------------------------------ */
 #define libcbase_assert(expr)                             \
-  ((void) ((expr) ? 0 :                                   \
+  ((void) (LIKELY(expr) ? 0 :                             \
            (ML_(libcbase_assert_fail)(#expr,              \
                                 __FILE__, __LINE__,       \
                                 __PRETTY_FUNCTION__))))