diff --git a/man3/posix_memalign.3 b/man3/posix_memalign.3
index 78b49bace..87dfc3cf9 100644
--- a/man3/posix_memalign.3
+++ b/man3/posix_memalign.3
@@ -35,7 +35,7 @@ posix_memalign, memalign, valloc, pvalloc \- Allocate aligned memory
 .sp
 .B #include <malloc.h>
 .sp
-.BI "void *memalign(size_t " boundary ", size_t " size );
+.BI "void *memalign(size_t " alignment ", size_t " size );
 .BI "void *pvalloc(size_t " size );
 .fi
 .sp
@@ -100,7 +100,7 @@ allocates
 .I size
 bytes and returns a pointer to the allocated memory.
 The memory address will be a multiple of
-.IR "boundary" ,
+.IR alignment ,
 which must be a power of two.
 .\" The behavior of memalign() for size==0 is as for posix_memalign()
 .\" but no standards govern this.
@@ -205,7 +205,7 @@ verifies that
 matches the requirements detailed above.
 .BR memalign ()
 may not check that the
-.I boundary
+.I alignment
 argument is correct.
 
 POSIX requires that memory obtained from