diff --git a/src/include/OpenImageIO/detail/fmt.h b/src/include/OpenImageIO/detail/fmt.h
index 74e6fae78c..6978311933 100644
--- a/src/include/OpenImageIO/detail/fmt.h
+++ b/src/include/OpenImageIO/detail/fmt.h
@@ -19,13 +19,18 @@
 #    define FMT_EXCEPTIONS 0
 #endif
 
-// Redefining FMT_THROW to something benign seems to avoid some UB or possibly
-// gcc 11+ compiler bug triggered by the definition of FMT_THROW in fmt 10.1+
-// when FMT_EXCEPTIONS=0, which results in mangling SIMD math. This nugget
-// below works around the problems for hard to understand reasons.
-#if !defined(FMT_THROW) && !FMT_EXCEPTIONS && OIIO_GNUC_VERSION >= 110000
-#    define FMT_THROW(x) \
-        OIIO_ASSERT_MSG(0, "fmt exception: %s", (x).what()), std::terminate()
+OIIO_NAMESPACE_BEGIN
+namespace pvt {
+OIIO_UTIL_API void
+log_fmt_error(const char* message);
+};
+OIIO_NAMESPACE_END
+
+// Redefining FMT_THROW to print and log the error. This should only occur if
+// we've made a mistake and mismatched a format string and its arguments.
+// Hopefully this will help us track it down.
+#if !defined(FMT_THROW) && !FMT_EXCEPTIONS
+#    define FMT_THROW(x) OIIO::pvt::log_fmt_error((x).what())
 #endif
 
 // Use the grisu fast floating point formatting for old fmt versions
diff --git a/src/include/OpenImageIO/strutil.h b/src/include/OpenImageIO/strutil.h
index e0c5ec302f..cb92333dcf 100644
--- a/src/include/OpenImageIO/strutil.h
+++ b/src/include/OpenImageIO/strutil.h
@@ -281,7 +281,11 @@ using sync::print;
 
 
 namespace pvt {
+// Internal use only
 OIIO_UTIL_API void debug(string_view str);
+OIIO_UTIL_API void append_error(string_view str);
+OIIO_UTIL_API bool has_error();
+OIIO_UTIL_API std::string geterror(bool clear);
 }
 
 /// `debug(format, ...)` prints debugging message when attribute "debug" is
diff --git a/src/include/imageio_pvt.h b/src/include/imageio_pvt.h
index 08fe2bb52f..4b854bcded 100644
--- a/src/include/imageio_pvt.h
+++ b/src/include/imageio_pvt.h
@@ -39,6 +39,7 @@ extern std::string output_format_list;
 extern std::string extension_list;
 extern std::string library_list;
 extern OIIO_UTIL_API int oiio_print_debug;
+extern OIIO_UTIL_API int oiio_print_uncaught_errors;
 extern int oiio_log_times;
 extern int openexr_core;
 extern int limit_channels;
diff --git a/src/libOpenImageIO/imageio.cpp b/src/libOpenImageIO/imageio.cpp
index e7712b19cc..ba859c607c 100644
--- a/src/libOpenImageIO/imageio.cpp
+++ b/src/libOpenImageIO/imageio.cpp
@@ -62,7 +62,6 @@ std::string output_format_list;  // comma-separated list of writable formats
 std::string extension_list;      // list of all extensions for all formats
 std::string library_list;        // list of all libraries for all formats
 int oiio_log_times = Strutil::stoi(Sysutil::getenv("OPENIMAGEIO_LOG_TIMES"));
-int oiio_print_uncaught_errors(1);
 std::vector<float> oiio_missingcolor;
 }  // namespace pvt
 
@@ -285,51 +284,10 @@ openimageio_version()
 
 
 
-// ErrorHolder houses a string, with the addition that when it is destroyed,
-// it will disgorge any un-retrieved error messages, in an effort to help
-// beginning users diagnose their problems if they have forgotten to call
-// geterror().
-struct ErrorHolder {
-    std::string error_msg;
-
-    ~ErrorHolder()
-    {
-        if (!error_msg.empty() && pvt::oiio_print_uncaught_errors) {
-            OIIO::print(
-                "OpenImageIO exited with a pending error message that was never\n"
-                "retrieved via OIIO::geterror(). This was the error message:\n{}\n",
-                error_msg);
-        }
-    }
-};
-
-
-
-// To avoid thread oddities, we have the storage area buffering error
-// messages for append_error()/geterror() be thread-specific.
-static thread_local ErrorHolder error_msg_holder;
-
-
 void
 pvt::append_error(string_view message)
 {
-    // Remove a single trailing newline
-    if (message.size() && message.back() == '\n')
-        message.remove_suffix(1);
-    std::string& error_msg(error_msg_holder.error_msg);
-    OIIO_ASSERT(
-        error_msg.size() < 1024 * 1024 * 16
-        && "Accumulated error messages > 16MB. Try checking return codes!");
-    // If we are appending to existing error messages, separate them with
-    // a single newline.
-    if (error_msg.size() && error_msg.back() != '\n')
-        error_msg += '\n';
-    error_msg += std::string(message);
-
-    // Remove a single trailing newline
-    if (message.size() && message.back() == '\n')
-        message.remove_suffix(1);
-    error_msg = std::string(message);
+    Strutil::pvt::append_error(message);
 }
 
 
@@ -337,8 +295,7 @@ pvt::append_error(string_view message)
 bool
 has_error()
 {
-    std::string& error_msg(error_msg_holder.error_msg);
-    return !error_msg.empty();
+    return Strutil::pvt::has_error();
 }
 
 
@@ -346,11 +303,7 @@ has_error()
 std::string
 geterror(bool clear)
 {
-    std::string& error_msg(error_msg_holder.error_msg);
-    std::string e = error_msg;
-    if (clear)
-        error_msg.clear();
-    return e;
+    return Strutil::pvt::geterror(clear);
 }
 
 
diff --git a/src/libutil/strutil.cpp b/src/libutil/strutil.cpp
index 2435afd534..1a39b7798a 100644
--- a/src/libutil/strutil.cpp
+++ b/src/libutil/strutil.cpp
@@ -172,9 +172,86 @@ OIIO_UTIL_API int
 OIIO_UTIL_API int
     oiio_print_debug(oiio_debug_env ? Strutil::stoi(oiio_debug_env) : 1);
 #endif
+OIIO_UTIL_API int oiio_print_uncaught_errors(1);
 }  // namespace pvt
 
 
+
+// ErrorHolder houses a string, with the addition that when it is destroyed,
+// it will disgorge any un-retrieved error messages, in an effort to help
+// beginning users diagnose their problems if they have forgotten to call
+// geterror().
+struct ErrorHolder {
+    std::string error_msg;
+
+    ~ErrorHolder()
+    {
+        if (!error_msg.empty() && pvt::oiio_print_uncaught_errors) {
+            OIIO::print(
+                "OpenImageIO exited with a pending error message that was never\n"
+                "retrieved via OIIO::geterror(). This was the error message:\n{}\n",
+                error_msg);
+        }
+    }
+};
+
+
+// To avoid thread oddities, we have the storage area buffering error
+// messages for append_error()/geterror() be thread-specific.
+static thread_local ErrorHolder error_msg_holder;
+
+
+void
+Strutil::pvt::append_error(string_view message)
+{
+    // Remove a single trailing newline
+    if (message.size() && message.back() == '\n')
+        message.remove_suffix(1);
+    std::string& error_msg(error_msg_holder.error_msg);
+    OIIO_ASSERT(
+        error_msg.size() < 1024 * 1024 * 16
+        && "Accumulated error messages > 16MB. Try checking return codes!");
+    // If we are appending to existing error messages, separate them with
+    // a single newline.
+    if (error_msg.size() && error_msg.back() != '\n')
+        error_msg += '\n';
+    error_msg += std::string(message);
+
+    // Remove a single trailing newline
+    if (message.size() && message.back() == '\n')
+        message.remove_suffix(1);
+    error_msg = std::string(message);
+}
+
+
+bool
+Strutil::pvt::has_error()
+{
+    std::string& error_msg(error_msg_holder.error_msg);
+    return !error_msg.empty();
+}
+
+
+std::string
+Strutil::pvt::geterror(bool clear)
+{
+    std::string& error_msg(error_msg_holder.error_msg);
+    std::string e = error_msg;
+    if (clear)
+        error_msg.clear();
+    return e;
+}
+
+
+void
+pvt::log_fmt_error(const char* message)
+{
+    print("fmt exception: {}\n", message);
+    Strutil::pvt::append_error(std::string("fmt exception: ") + message);
+}
+
+
+
 void
 Strutil::pvt::debug(string_view message)
 {
diff --git a/src/oiiotool/oiiotool.cpp b/src/oiiotool/oiiotool.cpp
index bcfcc7139e..3e8a261054 100644
--- a/src/oiiotool/oiiotool.cpp
+++ b/src/oiiotool/oiiotool.cpp
@@ -6395,6 +6395,12 @@ Oiiotool::getargs(int argc, char* argv[])
     ap.arg("--crash")
       .hidden()
       .action(crash_me);
+    ap.arg("--test-bad-format")
+      .hidden()
+      .action([&](cspan<const char*>){
+                  print("{}\n", Strutil::fmt::format("hey hey {:d} {}",
+                                                     "foo", "bar", "oops"));
+              });
 
     ap.separator("Commands that read images:");
     ap.arg("-i %s:FILENAME")
diff --git a/testsuite/oiiotool/ref/out.txt b/testsuite/oiiotool/ref/out.txt
index e5532a1f56..e5b24d1dfc 100644
--- a/testsuite/oiiotool/ref/out.txt
+++ b/testsuite/oiiotool/ref/out.txt
@@ -57,6 +57,12 @@ half data[2][2][3] =
   { /* (0, 1): */ { 0.000000000, 0.000000000, 0.000000000 },
     /* (1, 1): */ { 1.000000000, 1.000000000, 0.000000000 } },
 };
+testing bad format
+fmt exception: invalid format specifier
+hey hey foo bar
+OpenImageIO exited with a pending error message that was never
+retrieved via OIIO::geterror(). This was the error message:
+fmt exception: invalid format specifier
 Comparing "filled.tif" and "ref/filled.tif"
 PASS
 Comparing "autotrim.tif" and "ref/autotrim.tif"
diff --git a/testsuite/oiiotool/run.py b/testsuite/oiiotool/run.py
index 315406f7f0..ec5c661544 100755
--- a/testsuite/oiiotool/run.py
+++ b/testsuite/oiiotool/run.py
@@ -234,6 +234,9 @@
 command += oiiotool ("-echo dumpdata: --dumpdata dump.exr")
 command += oiiotool ("-echo dumpdata:C --dumpdata:C=data dump.exr")
 
+# Test printing uncaught errors (and finding bad fmt strings)
+command += oiiotool ("--echo \"testing bad format\" --test-bad-format")
+
 # To add more tests, just append more lines like the above and also add
 # the new 'feature.tif' (or whatever you call it) to the outputs list,
 # below.