diff --git a/niftilib/CMakeLists.txt b/niftilib/CMakeLists.txt
index 09d522d2..bdef6587 100644
--- a/niftilib/CMakeLists.txt
+++ b/niftilib/CMakeLists.txt
@@ -40,6 +40,13 @@ if(NIFTI_BUILD_TESTING AND NIFTI_BUILD_APPLICATIONS)
   add_executable(nifti_first_test_program nifti_tester001.c)
   target_link_libraries(nifti_first_test_program ${NIFTI_PACKAGE_PREFIX}niftiio )
 
+  add_executable(${NIFTI_PACKAGE_PREFIX}nifti_short_read_test nifti_short_read_test.c)
+  target_link_libraries(${NIFTI_PACKAGE_PREFIX}nifti_short_read_test ${NIFTI_NIFTILIB_NAME})
+  add_test(
+    NAME nifti_short_read_rejected
+    COMMAND $<TARGET_FILE:${NIFTI_PACKAGE_PREFIX}nifti_short_read_test>
+    )
+
   add_executable(nifti_second_test_program nifti_tester002.c)
   target_link_libraries(nifti_second_test_program ${NIFTI_PACKAGE_PREFIX}niftiio )
 
diff --git a/niftilib/nifti1_io.c b/niftilib/nifti1_io.c
index eb8887f3..7792d635 100644
--- a/niftilib/nifti1_io.c
+++ b/niftilib/nifti1_io.c
@@ -5019,7 +5019,7 @@ size_t nifti_read_buffer(znzFile fp, void* dataptr, size_t ntot,
   if( dataptr == NULL ){
      if( g_opts.debug > 0 )
         fprintf(stderr,"** ERROR: nifti_read_buffer: NULL dataptr\n");
-     return -1;
+     return 0;
   }
 
   ii = znzread( dataptr , 1 , ntot , fp ) ;             /* data input */
@@ -5034,7 +5034,7 @@ size_t nifti_read_buffer(znzFile fp, void* dataptr, size_t ntot,
                nim->iname , (unsigned int)ntot ,
                (unsigned int)ii , (unsigned int)(ntot-ii) ) ;
     /* memset( (char *)(dataptr)+ii , 0 , ntot-ii ) ;  now failure [rickr] */
-    return -1 ;
+    return 0 ;
   }
 
   if( g_opts.debug > 2 )
diff --git a/niftilib/nifti_short_read_test.c b/niftilib/nifti_short_read_test.c
new file mode 100644
index 00000000..809fb684
--- /dev/null
+++ b/niftilib/nifti_short_read_test.c
@@ -0,0 +1,89 @@
+/* A .nii whose data section is short of the header's declared size must be
+   rejected, not handed back with uninitialized tail bytes. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "nifti1_io.h"
+
+static const char *WHOLE = "short_read_whole.nii";
+static const char *SHORT = "short_read_short.nii";
+static const long MISSING = 1000;
+
+static int write_whole(void)
+{
+  int dims[8] = { 3, 31, 31, 31, 1, 1, 1, 1 };
+  nifti_image *nim = nifti_make_new_nim(dims, DT_FLOAT32, 1);
+  if( nim == NULL ) return 1;
+  if( nifti_set_filenames(nim, WHOLE, 0, 1) != 0 ){
+    nifti_image_free(nim);
+    return 1;
+  }
+  nifti_image_write(nim);
+  nifti_image_free(nim);
+  return 0;
+}
+
+static int copy_truncated(void)
+{
+  FILE *in = fopen(WHOLE, "rb"), *out;
+  long size;
+  char *buf;
+  size_t got;
+
+  if( in == NULL ) return 1;
+  fseek(in, 0, SEEK_END);
+  size = ftell(in);
+  fseek(in, 0, SEEK_SET);
+  if( size <= MISSING ){ fclose(in); return 1; }
+
+  buf = (char *)malloc((size_t)size);
+  if( buf == NULL ){ fclose(in); return 1; }
+  got = fread(buf, 1, (size_t)size, in);
+  fclose(in);
+  if( got != (size_t)size ){ free(buf); return 1; }
+
+  out = fopen(SHORT, "wb");
+  if( out == NULL ){ free(buf); return 1; }
+  fwrite(buf, 1, (size_t)(size - MISSING), out);
+  fclose(out);
+  free(buf);
+  return 0;
+}
+
+int main(void)
+{
+  nifti_image *nim;
+
+  if( write_whole() ){
+    fprintf(stderr, "FAILURE: could not write the reference image\n");
+    return 1;
+  }
+  if( copy_truncated() ){
+    fprintf(stderr, "FAILURE: could not write the truncated copy\n");
+    return 1;
+  }
+
+  nim = nifti_image_read(SHORT, 1);
+  if( nim != NULL ){
+    fprintf(stderr, "FAILURE: truncated image was accepted, nvox=%d\n",
+            (int)nim->nvox);
+    nifti_image_free(nim);
+    return 1;
+  }
+
+  /* the rejection must be specific to the short read */
+  nim = nifti_image_read(WHOLE, 1);
+  if( nim == NULL ){
+    fprintf(stderr, "FAILURE: the whole image was rejected\n");
+    return 1;
+  }
+  if( nim->data == NULL ){
+    fprintf(stderr, "FAILURE: the whole image came back with no data\n");
+    nifti_image_free(nim);
+    return 1;
+  }
+  nifti_image_free(nim);
+
+  printf("Short-read rejection test passed.\n");
+  return 0;
+}
diff --git a/znzlib/znzlib.c b/znzlib/znzlib.c
index 52b5665d..300a631e 100644
--- a/znzlib/znzlib.c
+++ b/znzlib/znzlib.c
@@ -145,7 +145,8 @@ size_t znzread(void* buf, size_t size, size_t nmemb, znzFile file)
     while( remain > 0 ) {
        n2read = (remain < ZNZ_MAX_BLOCK_SIZE) ? (unsigned)remain : ZNZ_MAX_BLOCK_SIZE;
        nread = gzread(file->zfptr, (void *)cbuf, n2read);
-       if( nread < 0 ) return nread; /* returns -1 on error */
+       /* 0, not gzread's -1: this returns size_t, where -1 is SIZE_MAX. */
+       if( nread < 0 ) return 0;
 
        remain -= nread;
        cbuf += nread;
@@ -178,8 +179,8 @@ size_t znzwrite(const void* buf, size_t size, size_t nmemb, znzFile file)
        n2write = (remain < ZNZ_MAX_BLOCK_SIZE) ? (unsigned)remain : ZNZ_MAX_BLOCK_SIZE;
        nwritten = gzwrite(file->zfptr, (const void *)cbuf, n2write);
 
-       /* gzread returns 0 on error, but in case that ever changes... */
-       if( nwritten < 0 ) return nwritten;
+       /* gzwrite returns 0 on error, but in case that ever changes... */
+       if( nwritten < 0 ) return 0;
 
        remain -= nwritten;
        cbuf += nwritten;