diff --git a/src/con_duct/__main__.py b/src/con_duct/__main__.py
index 3e4c5e2..402aa76 100755
--- a/src/con_duct/__main__.py
+++ b/src/con_duct/__main__.py
@@ -650,7 +650,7 @@ def format_field(self, value: Any, format_spec: str) -> Any:
             return self.NONE
         # if it is a composite :format!conversion, we need to split it
         if "!" in format_spec and format_spec.index("!") > 1:
-            format_spec, conversion = format_spec.split("!")
+            format_spec, conversion = format_spec.split("!", 1)
         else:
             conversion = None
         try:
diff --git a/test/test_formatter.py b/test/test_formatter.py
index 97fb35d..642aad5 100644
--- a/test/test_formatter.py
+++ b/test/test_formatter.py
@@ -334,3 +334,14 @@ def test_execution_summary_formatted_wall_clock_time_nowvalid(
         colors=colors,
     )
     assert f"Rendering: {GREEN}nan{STOP}" == report.execution_summary_formatted
+
+    # or if we really provide bad formatting, e.g. the opposite order of conversion and formatting
+    report = Report(
+        "_cmd",
+        [],
+        mock_log_paths,
+        "Rendering: {wall_clock_time!X:.3f}",
+        clobber=False,
+        colors=colors,
+    )
+    assert f"Rendering: {GREEN}nan{STOP}" == report.execution_summary_formatted