diff --git a/src/tiff.imageio/tiffinput.cpp b/src/tiff.imageio/tiffinput.cpp
index a08198f271..c09cb9d0c4 100644
--- a/src/tiff.imageio/tiffinput.cpp
+++ b/src/tiff.imageio/tiffinput.cpp
@@ -238,8 +238,10 @@ class TIFFInput final : public ImageInput {
     // like we think the file is hopelessly corrupted.
     bool readspec(bool read_meta = true);
 
-    // Figure out all the photometric-related aspects of the header
-    void readspec_photometric();
+    // Figure out all the photometric-related aspects of the header.
+    // Return true if all is fine, false if something really bad happens,
+    // like we think the file is invalid or hopelessly corrupted.
+    bool readspec_photometric();
 
     // Convert planar separate to contiguous data format
     void separate_to_contig(size_t nplanes, size_t nvals,
@@ -1205,6 +1207,7 @@ TIFFInput::readspec(bool read_meta)
     TIFFGetFieldDefaulted(m_tif, TIFFTAG_BITSPERSAMPLE, &m_bitspersample);
     m_spec.attribute("oiio:BitsPerSample", (int)m_bitspersample);
 
+    m_spec.set_format(TypeDesc::UNKNOWN);
     unsigned short sampleformat = SAMPLEFORMAT_UINT;
     TIFFGetFieldDefaulted(m_tif, TIFFTAG_SAMPLEFORMAT, &sampleformat);
     switch (m_bitspersample) {
@@ -1233,8 +1236,7 @@ TIFFInput::readspec(bool read_meta)
         else if (sampleformat == SAMPLEFORMAT_IEEEFP) {
             m_spec.set_format(TypeDesc::HALF);
             // Adobe extension, see http://chriscox.org/TIFFTN3d1.pdf
-        } else
-            m_spec.set_format(TypeDesc::UNKNOWN);
+        }
         break;
     case 24:
         // Make 24 bit look like 32 bit
@@ -1245,8 +1247,6 @@ TIFFInput::readspec(bool read_meta)
             m_spec.set_format(TypeDesc::UINT32);
         else if (sampleformat == SAMPLEFORMAT_INT)
             m_spec.set_format(TypeDesc::INT32);
-        else
-            m_spec.set_format(TypeDesc::UNKNOWN);
         break;
     case 64:
         if (sampleformat == SAMPLEFORMAT_IEEEFP)
@@ -1254,7 +1254,15 @@ TIFFInput::readspec(bool read_meta)
         else
             m_spec.set_format(TypeDesc::UNKNOWN);
         break;
-    default: m_spec.set_format(TypeDesc::UNKNOWN); break;
+    default:
+        errorfmt("Invalid bits per sample ({})", m_bitspersample);
+        return false;
+    }
+
+    if (m_spec.format == TypeUnknown) {
+        errorfmt("Invalid sampleformat value ({}) for {} bits per sample",
+                 sampleformat, m_bitspersample);
+        return false;
     }
 
     // Use the table for all the obvious things that can be mindlessly
@@ -1278,7 +1286,8 @@ TIFFInput::readspec(bool read_meta)
     TIFFGetField(m_tif, TIFFTAG_PHOTOMETRIC, &m_photometric);
     m_spec.attribute("tiff:PhotometricInterpretation", (int)m_photometric);
 
-    readspec_photometric();
+    if (!readspec_photometric())
+        return false;
 
     TIFFGetFieldDefaulted(m_tif, TIFFTAG_PLANARCONFIG, &m_planarconfig);
     m_separate = (m_planarconfig == PLANARCONFIG_SEPARATE
@@ -1579,7 +1588,7 @@ TIFFInput::readspec(bool read_meta)
 
 
 
-void
+bool
 TIFFInput::readspec_photometric()
 {
     switch (m_photometric) {
@@ -1651,6 +1660,12 @@ TIFFInput::readspec_photometric()
         m_spec.attribute("tiff:ColorSpace", "LOGLUV");
         break;
     case PHOTOMETRIC_PALETTE: {
+        if (m_bitspersample > 16) {
+            errorfmt(
+                "Palette images only support <= 16 bits per sample (was {})",
+                m_bitspersample);
+            return false;
+        }
         m_spec.attribute("tiff:ColorSpace", "palette");
         // Read the color map
         unsigned short *r = NULL, *g = NULL, *b = NULL;
@@ -1710,6 +1725,8 @@ TIFFInput::readspec_photometric()
         m_spec.attribute("oiio:ColorSpace",
                          m_spec.get_string_attribute("tiff:ColorSpace"));
     }
+
+    return true;
 }
 
 
diff --git a/testsuite/tiff-misc/ref/out-libtiff409.txt b/testsuite/tiff-misc/ref/out-libtiff409.txt
index 586ab85d4c..b8f9937118 100644
--- a/testsuite/tiff-misc/ref/out-libtiff409.txt
+++ b/testsuite/tiff-misc/ref/out-libtiff409.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"
diff --git a/testsuite/tiff-misc/ref/out-libtiff410.txt b/testsuite/tiff-misc/ref/out-libtiff410.txt
index 6dfebb0510..a8247397b4 100644
--- a/testsuite/tiff-misc/ref/out-libtiff410.txt
+++ b/testsuite/tiff-misc/ref/out-libtiff410.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"
diff --git a/testsuite/tiff-misc/ref/out-libtiff430.txt b/testsuite/tiff-misc/ref/out-libtiff430.txt
index 937600348d..1ba814e913 100644
--- a/testsuite/tiff-misc/ref/out-libtiff430.txt
+++ b/testsuite/tiff-misc/ref/out-libtiff430.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"
diff --git a/testsuite/tiff-misc/ref/out-libtiff470-b.txt b/testsuite/tiff-misc/ref/out-libtiff470-b.txt
index f4066a12af..4f9e90b485 100644
--- a/testsuite/tiff-misc/ref/out-libtiff470-b.txt
+++ b/testsuite/tiff-misc/ref/out-libtiff470-b.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"
diff --git a/testsuite/tiff-misc/ref/out-libtiff470.txt b/testsuite/tiff-misc/ref/out-libtiff470.txt
index b159cb3e74..c5df0c6b7d 100644
--- a/testsuite/tiff-misc/ref/out-libtiff470.txt
+++ b/testsuite/tiff-misc/ref/out-libtiff470.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"
diff --git a/testsuite/tiff-misc/ref/out.txt b/testsuite/tiff-misc/ref/out.txt
index 10a736f203..a067377d67 100644
--- a/testsuite/tiff-misc/ref/out.txt
+++ b/testsuite/tiff-misc/ref/out.txt
@@ -14,7 +14,7 @@ src/separate.tif     :  128 x  128, 3 channel, uint8 tiff
     tiff:RowsPerStrip: 7
 Comparing "src/separate.tif" and "separate.tif"
 PASS
-oiiotool ERROR: read : No support for data format of "src/corrupt1.tif"
+oiiotool ERROR: read : "src/corrupt1.tif": Invalid bits per sample (5)
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 --info -v src/corrupt1.tif
 oiiotool ERROR: read : File does not exist: "src/crash-1633.tif"