diff --git a/pyproject.toml b/pyproject.toml
index 1f7cf30..c1d966d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,7 +26,9 @@ accelerator-toolbox="*"
 numpy="<2.0"
 pymongo="*"
 lat2db="*"
-softioc="*"
+# waveforms of chars/strings
+softioc=">4.1"
+
 p4p="*"
 bact_device_models="*"
 pandas="*"
@@ -45,4 +47,4 @@ sphinx-rtd-theme = { version = "1.0.0", optional = true }
 sphinxcontrib-napoleon = { version = "0.7", optional = true }
 
 [tool.poetry.extras]
-docs = ["Sphinx", "sphinx-rtd-theme", "sphinxcontrib-napoleon"]
\ No newline at end of file
+docs = ["Sphinx", "sphinx-rtd-theme", "sphinxcontrib-napoleon"]