diff --git a/INSTALL.md b/INSTALL.md
index 07d9750687..ab04603419 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -44,5 +44,7 @@ libraries. You are on your own.
 `make clean; make` will compile librocksdb.a (RocskDB static library) and all
 the unit tests. You can run all unit tests with `make check`.
 
+For shared library builds, exec `make librocksdb.so` instead.
+
 If you followed the above steps and your compile or unit tests fail,
 please submit an issue: (https://github.com/facebook/rocksdb/issues)
diff --git a/build_tools/build_detect_platform b/build_tools/build_detect_platform
index 96a1fb3319..87c4c871dc 100755
--- a/build_tools/build_detect_platform
+++ b/build_tools/build_detect_platform
@@ -198,7 +198,7 @@ EOF
       }
 EOF
     if [ "$?" = 0 ]; then
-        COMMON_FLAGS="$PLATFORM_LDFLAGS -DROCKSDB_FALLOCATE_PRESENT"
+        COMMON_FLAGS="$COMMON_FLAGS -DROCKSDB_FALLOCATE_PRESENT"
     fi
 
     # Test whether Snappy library is installed