diff --git a/glibc.spec b/glibc.spec
index 525173f..4e95224 100644
--- a/glibc.spec
+++ b/glibc.spec
@@ -111,21 +111,19 @@
 # any lua %pre, %post, %postun, etc. sections to have them expand into
 # those scripts.  It only works in lua sections and not anywhere else.
 %global glibc_post_funcs %{expand:
--- We use lua posix.exec because there may be no shell that we can run
--- during glibc upgrade.  We used to implement much of %%post as a C
--- program, but from an overall maintenance perspective the lua in the
--- spec file was simpler and safer given the operations required.
+-- We use lua because there may be no shell that we can run during
+-- glibc upgrade. We used to implement much of %%post as a C program,
+-- but from an overall maintenance perspective the lua in the spec
+-- file was simpler and safer given the operations required.
 -- All lua code will be ignored by rpm-ostree; see:
 -- https://github.com/projectatomic/rpm-ostree/pull/1869
 -- If we add new lua actions to the %%post code we should coordinate
 -- with rpm-ostree and ensure that their glibc install is functional.
-function post_exec (program, ...)
-  local pid = posix.fork ()
-  if pid == 0 then
-    posix.exec (program, ...)
-    assert (nil)
-  elseif pid > 0 then
-    posix.wait (pid)
+--
+-- Note: We use _prefix because Fedora's UsrMove says so.
+function call_ldconfig ()
+  if not rpm.execute("%{_prefix}/sbin/ldconfig") then
+    io.stdout:write ("Error: call to %{_prefix}/sbin/ldconfig failed.\n")
   end
 end
 
@@ -133,12 +131,15 @@ function update_gconv_modules_cache ()
   local iconv_dir = "%{_libdir}/gconv"
   local iconv_cache = iconv_dir .. "/gconv-modules.cache"
   local iconv_modules = iconv_dir .. "/gconv-modules"
-  if (posix.utime (iconv_modules) == 0) then
-    if (posix.utime (iconv_cache) == 0) then
-      post_exec ("%{_prefix}/sbin/iconvconfig",
-		 "-o", iconv_cache,
-		 "--nostdlib",
-		 iconv_dir)
+  if posix.utime(iconv_modules) == 0 then
+    if posix.utime (iconv_cache) == 0 then
+      if not rpm.execute("%{_prefix}/sbin/iconvconfig",
+		         "-o", iconv_cache,
+		         "--nostdlib",
+		         iconv_dir)
+      then
+	io.stdout:write ("Error: call to %{_prefix}/sbin/iconvconfig failed.\n")
+      end
     else
       io.stdout:write ("Error: Missing " .. iconv_cache .. " file.\n")
     end
@@ -2047,8 +2048,7 @@ end
 -- the cache early to avoid any problems running binaries with
 -- the new glibc.
 
--- Note: We use _prefix because Fedora's UsrMove says so.
-post_exec ("%{_prefix}/sbin/ldconfig")
+call_ldconfig()
 
 -- (4) Update gconv modules cache.
 -- If the /usr/lib/gconv/gconv-modules.cache exists, then update it
@@ -2060,7 +2060,7 @@ update_gconv_modules_cache()
 
 -- (5) On upgrades, restart systemd if installed.  "systemctl -q" does
 -- not suppress the error message (which is common in chroots), so
--- open-code post_exec with standard error suppressed.
+-- open-code rpm.execute with standard error suppressed.
 if tonumber(arg[2]) >= 2
    and posix.access("%{_prefix}/bin/systemctl", "x")
 then