diff --git a/README.md b/README.md
index 80bc8ec..badcd54 100644
--- a/README.md
+++ b/README.md
@@ -29,3 +29,8 @@ isotopes to be searched for.
 If `verbose.enable` is set to `TRUE`, files of the form `(fragment number).txt`
 containing the `pattern.search` output will be printed to the directory
 specified in `verbose.outputdir`, assuming the directory already exists.
+
+## Additional Notes
+
+As windows does not allow forking, the number of cores used on it will be
+constrained to 1.
diff --git a/src/script.def.R b/src/script.def.R
index d3bd75a..50b043f 100644
--- a/src/script.def.R
+++ b/src/script.def.R
@@ -79,6 +79,9 @@ fragments <- max(table[, columns.spectra])
 
 # set use_cores to safe amount
 use_cores = min(use_cores, detectCores() - 1)
+if (.Platform$OS.type == "windows") {
+  use_cores=1L
+}
 
 # lower bound of indices per fragment
 # (sorting guarantees that data points of same fragment are together)