diff --git a/src/stage1/stage1.h b/src/stage1/stage1.h
index 59632b9877..6413914f6e 100644
--- a/src/stage1/stage1.h
+++ b/src/stage1/stage1.h
@@ -56,7 +56,7 @@ enum TargetSubsystem {
 
 
 // ABI warning
-// Synchronize with target.cpp::os_list
+// Synchronize with std.Target.Os.Tag and target.cpp::os_list
 enum Os {
     OsFreestanding,
     OsAnanas,
@@ -94,6 +94,9 @@ enum Os {
     OsWASI,
     OsEmscripten,
     OsUefi,
+    OsOpenCL,
+    OsGLSL450,
+    OsVulkan,
     OsOther,
 };
 
diff --git a/src/stage1/target.cpp b/src/stage1/target.cpp
index 6aa3cfcbd0..5a1e18e152 100644
--- a/src/stage1/target.cpp
+++ b/src/stage1/target.cpp
@@ -122,6 +122,9 @@ static const Os os_list[] = {
     OsWASI,
     OsEmscripten,
     OsUefi,
+    OsOpenCL,
+    OsGLSL450,
+    OsVulkan,
     OsOther,
 };
 
@@ -213,6 +216,9 @@ Os target_os_enum(size_t index) {
 ZigLLVM_OSType get_llvm_os_type(Os os_type) {
     switch (os_type) {
         case OsFreestanding:
+        case OsOpenCL:
+        case OsGLSL450:
+        case OsVulkan:
         case OsOther:
             return ZigLLVM_UnknownOS;
         case OsAnanas:
@@ -330,6 +336,9 @@ const char *target_os_name(Os os_type) {
         case OsHurd:
         case OsWASI:
         case OsEmscripten:
+        case OsOpenCL:
+        case OsGLSL450:
+        case OsVulkan:
             return ZigLLVMGetOSTypeName(get_llvm_os_type(os_type));
     }
     zig_unreachable();
@@ -733,6 +742,9 @@ uint32_t target_c_type_size_in_bits(const ZigTarget *target, CIntType id) {
         case OsAMDPAL:
         case OsHermitCore:
         case OsHurd:
+        case OsOpenCL:
+        case OsGLSL450:
+        case OsVulkan:
             zig_panic("TODO c type size in bits for this target");
     }
     zig_unreachable();
@@ -999,6 +1011,10 @@ ZigLLVM_EnvironmentType target_default_abi(ZigLLVM_ArchType arch, Os os) {
         case OsWASI:
         case OsEmscripten:
             return ZigLLVM_Musl;
+        case OsOpenCL:
+        case OsGLSL450:
+        case OsVulkan:
+            return ZigLLVM_UnknownEnvironment;
     }
     zig_unreachable();
 }