diff --git a/build-constraints.yaml b/build-constraints.yaml
index 104d3b01..b11a23d6 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3192,6 +3192,9 @@ packages:
         - criterion < 1.2
         - statistics < 0.14 # requires bigger criterion, criterion stopped on #2538
 
+        # https://github.com/camfort/camfort/issues/64
+        - fortran-src < 0.1.0.6
+
 
 # end of packages