diff --git a/test-pngtest.sh b/test-pngtest.sh
index aeeccc641..5d12f4acb 100755
--- a/test-pngtest.sh
+++ b/test-pngtest.sh
@@ -5,4 +5,4 @@ echo "Running tests.  For details see pngtest-log.txt"
 echo "============ pngtest pngtest.png ==============" > pngtest-log.txt
 
 echo "Running test-pngtest.sh"
-./pngtest ${srcdir}/pngtest.png >> pngtest-log.txt
+./pngtest ${srcdir}/pngtest.png >> pngtest-log.txt 2>&1
diff --git a/test-pngvalid-full.sh b/test-pngvalid-full.sh
index 4821241a5..366d095f3 100755
--- a/test-pngvalid-full.sh
+++ b/test-pngvalid-full.sh
@@ -15,7 +15,7 @@ do
    test "$gamma" = sbit      || opts="$opts --nogamma-sbit"
    test "$gamma" = 16-to-8   || opts="$opts --nogamma-16-to-8"
 
-   if ./pngvalid --nostandard $opts >> pngtest-log.txt
+   if ./pngvalid --nostandard $opts >> pngtest-log.txt 2>&1
    then
       echo "  PASS:" pngvalid "(gamma-$gamma)"
    else
diff --git a/test-pngvalid-simple.sh b/test-pngvalid-simple.sh
index ff98e3269..c62e11e7b 100755
--- a/test-pngvalid-simple.sh
+++ b/test-pngvalid-simple.sh
@@ -10,7 +10,7 @@ echo "Running test-pngvalid-simple.sh"
 for opts in "" --progressive-read --interlace \
    "--progressive-read --interlace"
 do
-   if ./pngvalid  --nogamma $opts >> pngtest-log.txt
+   if ./pngvalid  --nogamma $opts >> pngtest-log.txt 2>&1
    then
       echo "  PASS:" pngvalid --nogamma $opts
    else