diff --git a/conda_build/environ.py b/conda_build/environ.py
index 853da44e02..46aa4c9b76 100644
--- a/conda_build/environ.py
+++ b/conda_build/environ.py
@@ -580,7 +580,7 @@ def get_shlib_ext(host_platform):
         return ".dll"
     elif host_platform in ["osx", "darwin"]:
         return ".dylib"
-    elif host_platform.startswith("linux"):
+    elif host_platform.startswith("linux") or host_platform.startswith("emscripten"):
         return ".so"
     elif host_platform == "noarch":
         # noarch packages should not contain shared libraries, use the system
diff --git a/conda_build/metadata.py b/conda_build/metadata.py
index 33c3230573..101373b067 100644
--- a/conda_build/metadata.py
+++ b/conda_build/metadata.py
@@ -124,6 +124,9 @@ def get_selectors(config: Config) -> dict[str, bool]:
         linux=plat.startswith("linux-"),
         linux32=bool(plat == "linux-32"),
         linux64=bool(plat == "linux-64"),
+        emscripten=plat.startswith('emscripten-'),
+        emscripten32=bool(plat == 'emscripten-32'),
+        unix=plat.startswith(('linux-', 'osx-', 'emscripten-')),
         arm=plat.startswith("linux-arm"),
         osx=plat.startswith("osx-"),
         unix=plat.startswith(("linux-", "osx-")),
diff --git a/conda_build/utils.py b/conda_build/utils.py
index aa375790f3..4ffd0e25a3 100644
--- a/conda_build/utils.py
+++ b/conda_build/utils.py
@@ -113,6 +113,7 @@ def glob(pathname, recursive=True):
 mmap_PROT_WRITE = 0 if on_win else mmap.PROT_WRITE
 
 DEFAULT_SUBDIRS = {
+    "emscripten-32",
     "linux-64",
     "linux-32",
     "linux-s390x",