diff --git a/hostopts.h b/hostopts.h
index 501dfa7f..7595d504 100644
--- a/hostopts.h
+++ b/hostopts.h
@@ -311,6 +311,40 @@
                                            const for struct dirent   */
 
 
+/*-------------------------------------------------------------------*/
+/* Hard-coded Emscripten (WebAssembly) features and options...       */
+/*-------------------------------------------------------------------*/
+#elif defined(__EMSCRIPTEN__)           /* wasm32 (webmvs build)     */
+
+/* Emscripten defines __unix__ but not __linux__. Based on the Linux */
+/* block below: no fork (sh command), no SCSI tape, no FBA block     */
+/* devices, no mlock, and a small fixed device-thread limit (each    */
+/* thread is a Web Worker from a fixed-size pool).                   */
+
+#define DLL_IMPORT              extern
+#define DLL_EXPORT
+#define INL_DLL_IMPORT
+#define INL_DLL_EXPORT          extern
+#undef  TUNTAP_IFF_RUNNING_NEEDED       /* (no tuntap)               */
+#undef  OPTION_SCSI_TAPE                /* (NO SCSI tape support)    */
+#undef  OPTION_SCSI_ERASE_TAPE          /* (NOT supported)           */
+#undef  OPTION_SCSI_ERASE_GAP           /* (NOT supported)           */
+#undef  OPTION_FBA_BLKDEVICE            /* (no FBA BLKDEVICE support)*/
+#define MAX_DEVICE_THREADS          4   /* (worker pool is fixed)    */
+#define MIXEDCASE_FILENAMES_ARE_UNIQUE  /* ("Foo" and "fOo" unique)  */
+#undef  HAVE_FORK                       /* (no processes)            */
+#undef  HAVE_MLOCKALL                   /* (no-op in wasm)           */
+#undef  HAVE_MLOCK                      /* (no-op in wasm)           */
+#undef  HAVE_BASIC_KEEPALIVE            /* configure finds the TCP   */
+#undef  HAVE_PARTIAL_KEEPALIVE          /* keepalive symbols, but    */
+#undef  HAVE_FULL_KEEPALIVE             /* setsockopt gives ENOPROTOOPT */
+#define HOW_TO_IMPLEMENT_SH_COMMAND       USE_ANSI_SYSTEM_API_FOR_SH_COMMAND
+#define SET_CONSOLE_CURSOR_SHAPE_METHOD   CURSOR_SHAPE_NOT_SUPPORTED
+#undef  OPTION_EXTCURS                  /* Normal cursor handling    */
+#define SCANDIR_CONST_STRUCT_DIRENT     /* define if scandir uses
+                                           const for struct dirent   */
+
+
 /*-------------------------------------------------------------------*/
 /* Hard-coded GNU Linux-specific features and options...             */
 /*-------------------------------------------------------------------*/