Index: src/platform/POSIX/OFSubprocess.m
==================================================================
--- src/platform/POSIX/OFSubprocess.m
+++ src/platform/POSIX/OFSubprocess.m
@@ -375,11 +375,13 @@
 - (void)close
 {
 	if (_readPipe[0] == -1)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
-	[self closeForWriting];
+	if (_writePipe[1] != -1)
+		[self closeForWriting];
+
 	close(_readPipe[0]);
 
 	if (_pid != -1) {
 		kill(_pid, SIGTERM);
 		waitpid(_pid, &_status, WNOHANG);

Index: src/platform/Windows/OFSubprocess.m
==================================================================
--- src/platform/Windows/OFSubprocess.m
+++ src/platform/Windows/OFSubprocess.m
@@ -381,11 +381,13 @@
 - (void)close
 {
 	if (_readPipe[0] == NULL)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
-	[self closeForWriting];
+	if (_writePipe[1] != NULL)
+		[self closeForWriting];
+
 	CloseHandle(_readPipe[0]);
 
 	if (_handle != INVALID_HANDLE_VALUE) {
 		TerminateProcess(_handle, 0);
 		CloseHandle(_handle);