diff --git a/prjxray/fasm_assembler.py b/prjxray/fasm_assembler.py
index ca0597e1..c756212f 100644
--- a/prjxray/fasm_assembler.py
+++ b/prjxray/fasm_assembler.py
@@ -99,11 +99,10 @@ class FasmAssembler(object):
     def enable_feature(self, tile, feature, address, line):
         gridinfo = self.grid.gridinfo_at_tilename(tile)
 
-        def update_segbit(bit):
+        def update_segbit(block_type, bit):
             '''Set or clear a single bit in a segment at the given word column and word bit position'''
 
-            # TODO: How to determine if the feature targets BLOCK_RAM segment type?
-            bits = gridinfo.bits[grid.BlockType.CLB_IO_CLK]
+            bits = gridinfo.bits[block_type]
 
             seg_baseaddr = bits.base_address
             seg_word_base = bits.offset
@@ -125,23 +124,23 @@ class FasmAssembler(object):
 
         db_k = '%s.%s' % (gridinfo.tile_type, feature)
 
-        any_bits = False
+        any_bits = set()
 
         try:
-            for bit in segbits.feature_to_bits(db_k, address):
-                any_bits = True
-                update_segbit(bit)
+            for block_type, bit in segbits.feature_to_bits(db_k, address):
+                any_bits.add(block_type)
+                update_segbit(block_type, bit)
         except KeyError:
             raise FasmLookupError(
                 "Segment DB %s, key %s not found from line '%s'" %
                 (gridinfo.tile_type, db_k, line))
 
-        if any_bits:
+        for block_type in any_bits:
             # Mark all frames used by this tile as in use.
-            bits = gridinfo.bits[grid.BlockType.CLB_IO_CLK]
-            if tile not in self.seen_tile:
-                for frame in segbits.frames(bits):
-                    self.frames_in_use.add(frame)
+            bits = gridinfo.bits[block_type]
+            for frame in range(bits.base_address,
+                               bits.base_address + bits.frames):
+                self.frames_in_use.add(frame)
 
     def parse_fasm_filename(self, filename):
         missing_features = []
diff --git a/prjxray/tile_segbits.py b/prjxray/tile_segbits.py
index 69ab8318..cb6b8856 100644
--- a/prjxray/tile_segbits.py
+++ b/prjxray/tile_segbits.py
@@ -147,9 +147,9 @@ class TileSegbits(object):
         for block_type in self.segbits:
             if address == 0 and feature in self.segbits[block_type]:
                 for bit in self.segbits[block_type][feature]:
-                    yield bit
+                    yield block_type, bit
                 return
 
         block_type, feature = self.feature_addresses[feature][address]
         for bit in self.segbits[block_type][feature]:
-            yield bit
+            yield block_type, bit
diff --git a/utils/bit2fasm.py b/utils/bit2fasm.py
index 74caeb69..553a2973 100755
--- a/utils/bit2fasm.py
+++ b/utils/bit2fasm.py
@@ -43,7 +43,7 @@ def bits_to_fasm(db_root, bits_file, verbose, canonical):
         db_k = '%s.%s' % (gridinfo.tile_type, feature)
         segbits = db.get_tile_segbits(gridinfo.tile_type)
         any_bits = False
-        for bit in segbits.feature_to_bits(db_k):
+        for block_type, bit in segbits.feature_to_bits(db_k):
             if bit.isset:
                 any_bits = True