diff --git a/src/map/if/acd/acd66.hpp b/src/map/if/acd/acd66.hpp
index 92caf3b57..7d7a14faa 100644
--- a/src/map/if/acd/acd66.hpp
+++ b/src/map/if/acd/acd66.hpp
@@ -160,8 +160,10 @@ private:
     best_multiplicity = UINT32_MAX;
     best_free_set = UINT32_MAX;
 
+    uint32_t max_free_set = num_vars == 11 ? 5 : 4;
+
     /* find ACD "66" for different number of variables in the free set */
-    for ( uint32_t i = num_vars - 6; i <= 5; ++i )
+    for ( uint32_t i = num_vars - 6; i <= max_free_set; ++i )
     {
       if ( find_decomposition_bs( i ) )
         return true;
@@ -176,8 +178,10 @@ private:
     best_multiplicity = UINT32_MAX;
     best_free_set = UINT32_MAX;
 
+    uint32_t max_free_set = ( num_vars == 11 || offset == 5 ) ? 5 : 4;
+
     /* find ACD "66" for different number of variables in the free set */
-    for ( uint32_t i = std::max( num_vars - 6, offset ); i <= 5; ++i )
+    for ( uint32_t i = std::max( num_vars - 6, offset ); i <= max_free_set; ++i )
     {
       if ( find_decomposition_bs_offset( i, offset ) )
         return true;