diff --git a/src/cineon.imageio/cineoninput.cpp b/src/cineon.imageio/cineoninput.cpp
index 330ba34c27..48f50e0ff8 100644
--- a/src/cineon.imageio/cineoninput.cpp
+++ b/src/cineon.imageio/cineoninput.cpp
@@ -102,8 +102,20 @@ CineonInput::open(const std::string& name, ImageSpec& newspec)
     int maxbits = 0;
     for (int i = 0; i < nchannels; i++) {
         int b(m_cin.header.BitDepth(i));
-        if (b < 1 || b > 32) {
+        // libcineon's ComponentDataSize/ComponentByteCount only know how to
+        // handle these bit depths; anything else asserts (or worse, in a
+        // non-debug build) deep inside the vendored library. Reject bogus
+        // values here so we can give a proper error instead.
+        switch (b) {
+        case 8:
+        case 10:
+        case 12:
+        case 16:
+        case 32:
+        case 64: break;
+        default:
             errorfmt("Invalid bitdepth in channel {}: {} bits", i, b);
+            close();
             return false;
         }
         maxbits = std::max(maxbits, b);
diff --git a/testsuite/cineon/ref/out.txt b/testsuite/cineon/ref/out.txt
index 74ad31e404..07f06a1928 100644
--- a/testsuite/cineon/ref/out.txt
+++ b/testsuite/cineon/ref/out.txt
@@ -36,3 +36,6 @@ Reading ../oiio-images/cineon/checker.cin
 oiiotool ERROR: read : "src/broken_bitdepth.cin": Invalid number of channels 255 (must be 1-8)
 Full command line was:
 > oiiotool --info --hash src/broken_bitdepth.cin
+oiiotool ERROR: read : "src/broken_bitdepth2.cin": Invalid bitdepth in channel 0: 26 bits
+Full command line was:
+> oiiotool --info --hash src/broken_bitdepth2.cin
diff --git a/testsuite/cineon/run.py b/testsuite/cineon/run.py
index e73803c963..9e01f91ed5 100755
--- a/testsuite/cineon/run.py
+++ b/testsuite/cineon/run.py
@@ -14,5 +14,8 @@
 
 # Regression tests for broken files
 command += info_command ("src/broken_bitdepth.cin", verbose=False, failureok=True)
+# Regression test for a per-channel bit depth libcineon doesn't recognize
+# (used to assert/abort inside CineonHeader.cpp instead of erroring out).
+command += info_command ("src/broken_bitdepth2.cin", verbose=False, failureok=True)
 
 outputs = [ "out.txt" ]
diff --git a/testsuite/cineon/src/broken_bitdepth2.cin b/testsuite/cineon/src/broken_bitdepth2.cin
new file mode 100644
index 0000000000..fdee065778
Binary files /dev/null and b/testsuite/cineon/src/broken_bitdepth2.cin differ