Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -1855,17 +1855,11 @@
 
 		#if (!defined(TARGET_OS_IPHONE) || !TARGET_OS_IPHONE) && \
 		    (!defined(TARGET_OS_SIMULATOR) || !TARGET_OS_SIMULATOR)
 		egrep_cpp_yes
 		#endif
-	], [
-		AC_MSG_RESULT(yes)
-		have_subprocesses="yes"
-
-		AC_CHECK_FUNCS(posix_spawnp)
-		AC_CHECK_HEADERS(spawn.h)
-	], [
+	], [], [
 		AC_MSG_RESULT(no)
 		have_subprocesses="no"
 	])
 	;;
 mingw*)
@@ -1872,21 +1866,22 @@
 	have_subprocesses="yes"
 	;;
 msdosdjgpp*)
 	have_subprocesses="no"
 	;;
-*)
+esac
+AS_IF([test x"$have_subprocesses" = x""], [
 	AC_HEADER_SYS_WAIT
 	AC_CHECK_FUNCS(kill)
 
 	AC_CHECK_FUNCS(posix_spawnp, [
 		AS_IF([test x"$ac_cv_func_kill" = x"yes"], [
-			have_subprocesses="yes"
-
-			AC_CHECK_HEADERS(spawn.h)
+			AC_CHECK_HEADERS(spawn.h, [have_subprocesses="yes"])
 		])
-	], [
+	])
+
+	AS_IF([test x"$have_subprocesses" = x""], [
 		AC_CHECK_FUNCS([vfork dup2 execvp _exit], [
 			AS_IF([test x"$ac_cv_func_vfork" = x"yes" \
 			    -a x"$ac_cv_func_pipe" = x"yes" \
 			    -a x"$ac_cv_func_dup2" = x"yes" \
 			    -a x"$ac_cv_func_execvp" = x"yes" \
@@ -1896,12 +1891,11 @@
 			])
 		], [
 			break
 		])
 	])
-	;;
-esac
+])
 AS_IF([test x"$have_subprocesses" = x"yes"], [
 	AC_SUBST(OF_SUBPROCESS_M, "OFSubprocess.m")
 	AC_DEFINE(OF_HAVE_SUBPROCESSES, 1, [Whether we have subprocesses])
 ])
 

Index: src/platform/POSIX/OFSubprocess.m
==================================================================
--- src/platform/POSIX/OFSubprocess.m
+++ src/platform/POSIX/OFSubprocess.m
@@ -39,11 +39,11 @@
 #import "OFNotOpenException.h"
 #import "OFOutOfRangeException.h"
 #import "OFReadFailedException.h"
 #import "OFWriteFailedException.h"
 
-#ifndef HAVE_POSIX_SPAWNP
+#if !defined(HAVE_POSIX_SPAWNP) || !defined(HAVE_SPAWN_H)
 extern char **environ;
 #endif
 
 @interface OFSubprocess ()
 - (void)of_getArgv: (char ***)argv
@@ -141,11 +141,11 @@
 		  forProgramName: programName
 		    andArguments: arguments];
 
 		@try {
 			env = [self of_environmentForDictionary: environment];
-#ifdef HAVE_POSIX_SPAWNP
+#if defined(HAVE_POSIX_SPAWNP) && defined(HAVE_SPAWN_H)
 			posix_spawn_file_actions_t actions;
 			posix_spawnattr_t attr;
 
 			if (posix_spawn_file_actions_init(&actions) != 0)
 				@throw [OFInitializationFailedException