diff --git a/NEWS b/NEWS
index 59ee31579..bc85c63f2 100644
--- a/NEWS
+++ b/NEWS
@@ -12,7 +12,7 @@ New in spot 0.9.2 (2012-07-02):
       node table for better cache-friendliness.  The resulting speedup
       is around 5% on BDD-intensive algorithms.
     - A new BDD operation, called bdd_implies() has been added to
-      BuDDy to check wether one BDD implies another.  This benefits
+      BuDDy to check whether one BDD implies another.  This benefits
       mostly the simulation and degeneralization algorithms of Spot.
     - A new offline implementation of the degeneralization (which
       had always been performed on-the-fly so far) available.  This
diff --git a/buddy/src/bddop.c b/buddy/src/bddop.c
index 975a6ef8d..bb79c7838 100644
--- a/buddy/src/bddop.c
+++ b/buddy/src/bddop.c
@@ -903,7 +903,7 @@ NAME    {* bdd\_implies *}
 SECTION {* operator *}
 SHORT   {* check whether one BDD implies another *}
 PROTO   {* int bdd_setxor(BDD l, BDD r) *}
-DESCR   {* Check wether $l$ implies $r$, or whether $r$ contains $l$. *}
+DESCR   {* Check whether $l$ implies $r$, or whether $r$ contains $l$. *}
 RETURN  {* 1 if $l$ implies $r$, 0 otherwise *}
 */
 int bdd_implies(BDD l, BDD r)
diff --git a/m4/valgrind.m4 b/m4/valgrind.m4
index 0453d8168..440b6d513 100644
--- a/m4/valgrind.m4
+++ b/m4/valgrind.m4
@@ -22,7 +22,7 @@ AC_DEFUN([_AX_CHECK_VALGRIND_SANITY],
 AC_DEFUN([AX_CHECK_VALGRIND], [
   AC_CHECK_PROG([VALGRIND], [valgrind], [valgrind])
   if test -n "$VALGRIND"; then
-    AC_CACHE_CHECK([wether valgrind is sane],
+    AC_CACHE_CHECK([whether valgrind is sane],
 		   [ax_cv_valgrind_sanity],
 		   [_AX_CHECK_VALGRIND_SANITY([ax_cv_valgrind_sanity=yes],
 					      [ax_cv_valgrind_sanity=no])])