diff --git a/iconv/Makefile b/iconv/Makefile
index f6631e861d..74cd9bf860 100644
--- a/iconv/Makefile
+++ b/iconv/Makefile
@@ -44,7 +44,7 @@ CFLAGS-linereader.c += -DNO_TRANSLITERATION
 CFLAGS-simple-hash.c += -I../locale
 
 tests	= tst-iconv1 tst-iconv2 tst-iconv3 tst-iconv4 tst-iconv5 tst-iconv6 \
-	  tst-iconv-mt
+	  tst-iconv7 tst-iconv-mt
 
 others		= iconv_prog iconvconfig
 install-others-programs	= $(inst_bindir)/iconv
diff --git a/iconv/gconv_simple.c b/iconv/gconv_simple.c
index 35aaa8aacd..75ce8fb1f4 100644
--- a/iconv/gconv_simple.c
+++ b/iconv/gconv_simple.c
@@ -76,7 +76,7 @@ __attribute ((always_inline))
 internal_ucs4_loop (struct __gconv_step *step,
 		    struct __gconv_step_data *step_data,
 		    const unsigned char **inptrp, const unsigned char *inend,
-		    unsigned char **outptrp, unsigned char *outend,
+		    unsigned char **outptrp, const unsigned char *outend,
 		    size_t *irreversible)
 {
   const unsigned char *inptr = *inptrp;
@@ -120,7 +120,8 @@ internal_ucs4_loop_unaligned (struct __gconv_step *step,
 			      struct __gconv_step_data *step_data,
 			      const unsigned char **inptrp,
 			      const unsigned char *inend,
-			      unsigned char **outptrp, unsigned char *outend,
+			      unsigned char **outptrp,
+			      const unsigned char *outend,
 			      size_t *irreversible)
 {
   const unsigned char *inptr = *inptrp;
@@ -169,7 +170,8 @@ internal_ucs4_loop_single (struct __gconv_step *step,
 			   struct __gconv_step_data *step_data,
 			   const unsigned char **inptrp,
 			   const unsigned char *inend,
-			   unsigned char **outptrp, unsigned char *outend,
+			   unsigned char **outptrp,
+			   const unsigned char *outend,
 			   size_t *irreversible)
 {
   mbstate_t *state = step_data->__statep;
@@ -231,7 +233,7 @@ __attribute ((always_inline))
 ucs4_internal_loop (struct __gconv_step *step,
 		    struct __gconv_step_data *step_data,
 		    const unsigned char **inptrp, const unsigned char *inend,
-		    unsigned char **outptrp, unsigned char *outend,
+		    unsigned char **outptrp, const unsigned char *outend,
 		    size_t *irreversible)
 {
   int flags = step_data->__flags;
@@ -298,7 +300,8 @@ ucs4_internal_loop_unaligned (struct __gconv_step *step,
 			      struct __gconv_step_data *step_data,
 			      const unsigned char **inptrp,
 			      const unsigned char *inend,
-			      unsigned char **outptrp, unsigned char *outend,
+			      unsigned char **outptrp,
+			      const unsigned char *outend,
 			      size_t *irreversible)
 {
   int flags = step_data->__flags;
@@ -368,7 +371,8 @@ ucs4_internal_loop_single (struct __gconv_step *step,
 			   struct __gconv_step_data *step_data,
 			   const unsigned char **inptrp,
 			   const unsigned char *inend,
-			   unsigned char **outptrp, unsigned char *outend,
+			   unsigned char **outptrp,
+			   const unsigned char *outend,
 			   size_t *irreversible)
 {
   mbstate_t *state = step_data->__statep;
@@ -443,7 +447,7 @@ __attribute ((always_inline))
 internal_ucs4le_loop (struct __gconv_step *step,
 		      struct __gconv_step_data *step_data,
 		      const unsigned char **inptrp, const unsigned char *inend,
-		      unsigned char **outptrp, unsigned char *outend,
+		      unsigned char **outptrp, const unsigned char *outend,
 		      size_t *irreversible)
 {
   const unsigned char *inptr = *inptrp;
@@ -488,7 +492,8 @@ internal_ucs4le_loop_unaligned (struct __gconv_step *step,
 				struct __gconv_step_data *step_data,
 				const unsigned char **inptrp,
 				const unsigned char *inend,
-				unsigned char **outptrp, unsigned char *outend,
+				unsigned char **outptrp,
+				const unsigned char *outend,
 				size_t *irreversible)
 {
   const unsigned char *inptr = *inptrp;
@@ -540,7 +545,8 @@ internal_ucs4le_loop_single (struct __gconv_step *step,
 			     struct __gconv_step_data *step_data,
 			     const unsigned char **inptrp,
 			     const unsigned char *inend,
-			     unsigned char **outptrp, unsigned char *outend,
+			     unsigned char **outptrp,
+			     const unsigned char *outend,
 			     size_t *irreversible)
 {
   mbstate_t *state = step_data->__statep;
@@ -601,7 +607,7 @@ __attribute ((always_inline))
 ucs4le_internal_loop (struct __gconv_step *step,
 		      struct __gconv_step_data *step_data,
 		      const unsigned char **inptrp, const unsigned char *inend,
-		      unsigned char **outptrp, unsigned char *outend,
+		      unsigned char **outptrp, const unsigned char *outend,
 		      size_t *irreversible)
 {
   int flags = step_data->__flags;
@@ -671,7 +677,8 @@ ucs4le_internal_loop_unaligned (struct __gconv_step *step,
 				struct __gconv_step_data *step_data,
 				const unsigned char **inptrp,
 				const unsigned char *inend,
-				unsigned char **outptrp, unsigned char *outend,
+				unsigned char **outptrp,
+				const unsigned char *outend,
 				size_t *irreversible)
 {
   int flags = step_data->__flags;
@@ -745,7 +752,8 @@ ucs4le_internal_loop_single (struct __gconv_step *step,
 			     struct __gconv_step_data *step_data,
 			     const unsigned char **inptrp,
 			     const unsigned char *inend,
-			     unsigned char **outptrp, unsigned char *outend,
+			     unsigned char **outptrp,
+			     const unsigned char *outend,
 			     size_t *irreversible)
 {
   mbstate_t *state = step_data->__statep;
diff --git a/iconv/skeleton.c b/iconv/skeleton.c
index cc39fdcc70..d43fac7683 100644
--- a/iconv/skeleton.c
+++ b/iconv/skeleton.c
@@ -597,6 +597,10 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 	  inptr = *inptrp;
 	  /* The outbuf buffer is empty.  */
 	  outstart = outbuf;
+#ifdef RESET_INPUT_BUFFER
+	  size_t loop_irreversible
+	    = lirreversible + (irreversible ? *irreversible : 0);
+#endif
 
 #ifdef SAVE_RESET_STATE
 	  SAVE_RESET_STATE (1);
@@ -671,8 +675,16 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 		  if (__glibc_unlikely (outerr != outbuf))
 		    {
 #ifdef RESET_INPUT_BUFFER
-		      RESET_INPUT_BUFFER;
-#else
+		      if (loop_irreversible
+			  == lirreversible + (irreversible ? *irreversible : 0))
+			{
+			  /* RESET_INPUT_BUFFER can only work if there
+			     were no irreversible characters during the
+			     last loop.  */
+			  RESET_INPUT_BUFFER;
+			  goto done_reset;
+			}
+#endif
 		      /* We have a problem in one of the functions below.
 			 Undo the conversion upto the error point.  */
 		      size_t nstatus __attribute__ ((unused));
@@ -682,9 +694,9 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 		      outbuf = outstart;
 
 		      /* Restore the state.  */
-# ifdef SAVE_RESET_STATE
+#ifdef SAVE_RESET_STATE
 		      SAVE_RESET_STATE (0);
-# endif
+#endif
 
 		      if (__glibc_likely (!unaligned))
 			{
@@ -701,7 +713,7 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 					       lirreversiblep
 					       EXTRA_LOOP_ARGS);
 			}
-# if POSSIBLY_UNALIGNED
+#if POSSIBLY_UNALIGNED
 		      else
 			{
 			  if (FROM_DIRECTION)
@@ -720,7 +732,7 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 							       lirreversiblep
 							       EXTRA_LOOP_ARGS);
 			}
-# endif
+#endif
 
 		      /* We must run out of output buffer space in this
 			 rerun.  */
@@ -731,9 +743,11 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
 			 the invocation counter.  */
 		      if (__glibc_unlikely (outbuf == outstart))
 			--data->__invocation_counter;
-#endif	/* reset input buffer */
 		    }
 
+#ifdef RESET_INPUT_BUFFER
+		done_reset:
+#endif
 		  /* Change the status.  */
 		  status = result;
 		}
diff --git a/iconv/tst-iconv7.c b/iconv/tst-iconv7.c
new file mode 100644
index 0000000000..ee793d2f3e
--- /dev/null
+++ b/iconv/tst-iconv7.c
@@ -0,0 +1,67 @@
+/* Test iconv buffer handling with the IGNORE error handler.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Derived from BZ #18830 */
+#include <errno.h>
+#include <iconv.h>
+#include <stdio.h>
+
+
+static int
+do_test (void)
+{
+  iconv_t cd = iconv_open ("ASCII//IGNORE", "ASCII");
+  if (cd == (iconv_t) -1)
+    {
+      puts ("iconv_open failed");
+      return 1;
+    }
+
+  char input[5 + 3] = { 0, 0, 0, 0, 0, '1', '\200', '2' };
+  char *inptr = input;
+  size_t insize = sizeof (input);
+  char output[5];
+  char *outptr = output;
+  size_t outsize = sizeof (output);
+
+  size_t ret = iconv (cd, &inptr, &insize, &outptr, &outsize);
+  if (ret != (size_t) -1)
+    {
+      puts ("iconv succeeded");
+      return 1;
+    }
+  if (errno != E2BIG)
+    {
+      puts ("iconv did not set errno to E2BIG");
+      return 1;
+    }
+  if (inptr != input + sizeof (output) - outsize)
+    {
+      printf ("iconv consumed %td characters\n", inptr - input);
+      return 1;
+    }
+
+  if (iconv_close (cd) == -1)
+    {
+      puts ("iconv_close failed");
+      return 1;
+    }
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/s390/multiarch/gconv_simple.c b/sysdeps/s390/multiarch/gconv_simple.c
index ce7bcf541e..2861b6dacb 100644
--- a/sysdeps/s390/multiarch/gconv_simple.c
+++ b/sysdeps/s390/multiarch/gconv_simple.c
@@ -404,7 +404,7 @@ ICONV_VX_NAME (internal_ucs4le_loop) (struct __gconv_step *step,
 				      const unsigned char **inptrp,
 				      const unsigned char *inend,
 				      unsigned char **outptrp,
-				      unsigned char *outend,
+				      const unsigned char *outend,
 				      size_t *irreversible)
 {
   const unsigned char *inptr = *inptrp;
@@ -504,7 +504,7 @@ ICONV_VX_NAME (ucs4_internal_loop) (struct __gconv_step *step,
 				    const unsigned char **inptrp,
 				    const unsigned char *inend,
 				    unsigned char **outptrp,
-				    unsigned char *outend,
+				    const unsigned char *outend,
 				    size_t *irreversible)
 {
   int flags = step_data->__flags;
@@ -631,7 +631,7 @@ ICONV_VX_NAME (ucs4le_internal_loop) (struct __gconv_step *step,
 				      const unsigned char **inptrp,
 				      const unsigned char *inend,
 				      unsigned char **outptrp,
-				      unsigned char *outend,
+				      const unsigned char *outend,
 				      size_t *irreversible)
 {
   int flags = step_data->__flags;
