diff --git a/src/psd.imageio/psdinput.cpp b/src/psd.imageio/psdinput.cpp
index e22617db63..beb511b88e 100644
--- a/src/psd.imageio/psdinput.cpp
+++ b/src/psd.imageio/psdinput.cpp
@@ -1013,25 +1013,36 @@ PSDInput::validate_header()
         errorfmt("[Header] invalid depth {}", m_header.depth);
         return false;
     }
-    if (m_WantRaw)
-        return true;
-
-    //There are other (undocumented) color modes not listed here
+    // Reject any color mode outside the known set before the RawColor early
+    // return below: setup() indexes mode_channel_count/mode_channel_names by
+    // m_header.color_mode unconditionally (even for raw reads), so an
+    // out-of-table value (or one of the undocumented gaps, e.g. 5 and 6)
+    // must never reach that point regardless of m_WantRaw.
     switch (m_header.color_mode) {
     case ColorMode_Bitmap:
     case ColorMode_Indexed:
     case ColorMode_RGB:
     case ColorMode_Grayscale:
     case ColorMode_CMYK:
-    case ColorMode_Multichannel: break;
+    case ColorMode_Multichannel:
     case ColorMode_Duotone:
-    case ColorMode_Lab:
-        errorfmt("[Header] unsupported color mode {:d}", m_header.color_mode);
-        return false;
+    case ColorMode_Lab: break;
     default:
         errorfmt("[Header] unrecognized color mode {:d}", m_header.color_mode);
         return false;
     }
+
+    if (m_WantRaw)
+        return true;
+
+    // Duotone and Lab are only supported via the raw path (handled above).
+    switch (m_header.color_mode) {
+    case ColorMode_Duotone:
+    case ColorMode_Lab:
+        errorfmt("[Header] unsupported color mode {:d}", m_header.color_mode);
+        return false;
+    default: break;
+    }
     return true;
 }
 
diff --git a/testsuite/psd-colormodes/ref/out.txt b/testsuite/psd-colormodes/ref/out.txt
index 18975023b1..bce87a0473 100644
--- a/testsuite/psd-colormodes/ref/out.txt
+++ b/testsuite/psd-colormodes/ref/out.txt
@@ -23,6 +23,10 @@ indexed-transparency-0.psd :  200 x  150, 4 channel, uint8 psd
 indexed-transparency-255.psd :  200 x  150, 4 channel, uint8 psd
     SHA-1: BEF32B02F44B369E39670DC2E2D2D1578B4998AD
 indexed-transparency-256-rejected
+oiiotool ERROR: read : [Header] unrecognized color mode 20
+failed to open "src/bad_colormode.psd": failed load_header
+Full command line was:
+> oiiotool --nostderr --info --iconfig oiio:RawColor 1 src/bad_colormode.psd
 Comparing "pattern2-8-rgb.psd.tif" and "ref/pattern2.tif"
 PASS
 Comparing "pattern2-16-rgb.psd.tif" and "ref/pattern2.tif"
diff --git a/testsuite/psd-colormodes/run.py b/testsuite/psd-colormodes/run.py
index d94641bf96..4dbb444958 100755
--- a/testsuite/psd-colormodes/run.py
+++ b/testsuite/psd-colormodes/run.py
@@ -35,4 +35,7 @@
                     + "out.null > /dev/null 2>&1 "
                     + "|| echo indexed-transparency-256-rejected)")
 
+# Regression test: bad colormode
+command += oiiotool ("--nostderr --info --iconfig oiio:RawColor 1 src/bad_colormode.psd", failureok=True)
+
 outputs += [ "out.txt" ]
diff --git a/testsuite/psd-colormodes/src/bad_colormode.psd b/testsuite/psd-colormodes/src/bad_colormode.psd
new file mode 100644
index 0000000000..3d442899a9
Binary files /dev/null and b/testsuite/psd-colormodes/src/bad_colormode.psd differ