diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index de4ca2e7e0..723ed2ca1a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-08  Robert O'Callahan  <robert@ocallahan.org>
+
+	PR exp/18617
+	* ax-gdb.c (gen_conversion): Extend to 'to' bits, not 'from'.
+
 2015-07-08  Markus Metzger  <markus.t.metzger@intel.com>
 
 	* MAINTAINERS (Write After Approval): Add Markus T. Metzger.
diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c
index 7a9d1e7a8f..38dacac846 100644
--- a/gdb/ax-gdb.c
+++ b/gdb/ax-gdb.c
@@ -885,7 +885,7 @@ gen_conversion (struct agent_expr *ax, struct type *from, struct type *to)
   /* If we're converting to a narrower type, then we need to clear out
      the upper bits.  */
   if (TYPE_LENGTH (to) < TYPE_LENGTH (from))
-    gen_extend (ax, from);
+    gen_extend (ax, to);
 
   /* If the two values have equal width, but different signednesses,
      then we need to extend.  */
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c5386b2830..285bf2cf6b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-08  Robert O'Callahan  <robert@ocallahan.org>
+
+	PR exp/18617
+	* gdb.trace/ax.exp: Add test.
+
 2015-07-07  Yao Qi  <yao.qi@linaro.org>
 
 	* gdb.arch/aarch64-atomic-inst.exp: Check is_aarch64_target
diff --git a/gdb/testsuite/gdb.trace/ax.exp b/gdb/testsuite/gdb.trace/ax.exp
index e3d0479d92..d0644756fb 100644
--- a/gdb/testsuite/gdb.trace/ax.exp
+++ b/gdb/testsuite/gdb.trace/ax.exp
@@ -80,6 +80,8 @@ gdb_test "maint agent &gdb_long_test == &gdb_short_test" "" "maint agent &gdb_lo
 
 gdb_test "maint agent &gdb_long_test < &gdb_short_test" "" "maint agent &gdb_long_test < &gdb_short_test"
 
+gdb_test "maint agent (unsigned char)1L" ".*ext 8.*" "maint agent (unsigned char)1L"
+
 # Now test eval version of agent expressions.
 
 gdb_test "maint agent-eval 12" ".*const8 12.*end.*" "maint agent-eval 12"