diff --git a/src/mono/wasm/runtime/driver.c b/src/mono/wasm/runtime/driver.c
index 9dd130ce43954..6e0d65f7e9824 100644
--- a/src/mono/wasm/runtime/driver.c
+++ b/src/mono/wasm/runtime/driver.c
@@ -220,7 +220,7 @@ mono_wasm_assembly_already_added (const char *assembly_name)
 
 	WasmAssembly *entry = assemblies;
 	while (entry != NULL) {
-		int entry_name_minus_extn_len = strlen(entry->assembly.name) - 4;
+		int entry_name_minus_extn_len = strrchr (entry->assembly.name, '.') - entry->assembly.name;
 		if (entry_name_minus_extn_len == strlen(assembly_name) && strncmp (entry->assembly.name, assembly_name, entry_name_minus_extn_len) == 0)
 			return 1;
 		entry = entry->next;