diff --git a/src/frontc/cabs2cil.ml b/src/frontc/cabs2cil.ml
index 707612f6b..7fbe8db5f 100644
--- a/src/frontc/cabs2cil.ml
+++ b/src/frontc/cabs2cil.ml
@@ -2340,13 +2340,6 @@ let integerArrayLength (leno: exp option) : int =
                d_exp len)
   end
 
-(* sm: I'm sure something like this already exists, but ... *)
-let isNone (o : 'a option) : bool =
-  match o with
-  | None -> true
-  | Some _ -> false
-
-
 let annonCompFieldNameId = ref 0
 let annonCompFieldName = "__annonCompField"
 
@@ -5364,7 +5357,7 @@ and doInit
 	  (* ISO 6.7.8 para 14: final NUL added only if no size specified, or
 	     if there is room for it; btw, we can't rely on zero-init of
 	     globals, since this array might be a local variable *)
-          if ((isNone leno) || ((String.length s) < (integerArrayLength leno)))
+          if ((Option.is_none leno) || ((String.length s) < (integerArrayLength leno)))
             then ref [init Int64.zero]
             else ref []
         in
@@ -5426,7 +5419,7 @@ and doInit
 	  (* ISO 6.7.8 para 14: final NUL added only if no size specified, or
 	     if there is room for it; btw, we can't rely on zero-init of
 	     globals, since this array might be a local variable *)
-          if ((isNone leno) || ((List.length s) < (integerArrayLength leno)))
+          if ((Option.is_none leno) || ((List.length s) < (integerArrayLength leno)))
             then [init Int64.zero]
             else [])
 (*
@@ -5590,6 +5583,28 @@ and doInit
 
    (* We have a designator *)
   | _, (what, ie) :: restil when what != A.NEXT_INIT ->
+      let rec unrollDesignatorForNestedAnonymous (comp: compinfo) (designator: string) (whatnext: initwhat) =
+        let own_field = List.filter (fun fld -> fld.fname = designator) comp.cfields in
+        match own_field with
+        | fld :: _ -> (true, Some(A.INFIELD_INIT (designator, whatnext)))
+        | [] ->
+          let anonymous_compounds = List.filter_map (fun f ->
+              (* f.ftype need not be unrolled here, inner anonymous struct cannot be typdef'ed *)
+              match f.ftype with
+              | TComp(compinfo, _) when prefix annonCompFieldName f.fname  -> Some (f, compinfo)
+              | _ -> None
+            ) comp.cfields
+          in
+          let anonymous_compound_inits = List.filter_map (fun (comp_field, comp) ->
+              match unrollDesignatorForNestedAnonymous comp designator whatnext with
+              | _, Some(what) -> Some(comp_field, what)
+              | _, None -> None
+            ) anonymous_compounds
+          in
+          match anonymous_compound_inits with
+          | [] -> (false, None)
+          | (comp_fld, compwhat) :: _ -> (false, Some(A.INFIELD_INIT (comp_fld.fname, compwhat)))
+      in
       (* Process a designator and position to the designated subobject *)
       let addressSubobj
           (so: subobj)
@@ -5604,10 +5619,17 @@ and doInit
           | A.INFIELD_INIT (fn, whatnext) -> begin
               match unrollType so.soTyp with
                 TComp (comp, _) ->
-                  let toinit = fieldsToInit comp (Some fn) in
-                  so.stack <- InComp(so.soOff, comp, toinit) :: so.stack;
-                  normalSubobj so;
-                  address whatnext acc
+                  let unrolledWhat = unrollDesignatorForNestedAnonymous comp fn whatnext in
+                  begin
+                    match unrolledWhat with
+                      false, Some(unrolled) ->
+                        address unrolled acc
+                    | _ ->
+                      let toinit = fieldsToInit comp (Some fn) in
+                      so.stack <- InComp(so.soOff, comp, toinit) :: so.stack;
+                      normalSubobj so;
+                      address whatnext acc
+                  end;
 
               | _ -> E.s (error "Field designator %s not in a struct " fn)
           end
diff --git a/test/small1/unioninit.c b/test/small1/unioninit.c
new file mode 100644
index 000000000..04d9a9d03
--- /dev/null
+++ b/test/small1/unioninit.c
@@ -0,0 +1,131 @@
+#include "testharness.h"
+typedef union
+{
+    struct
+    {
+        short leaf;
+    };
+    int raw;
+} un;
+
+typedef unsigned int uint32_t;
+typedef unsigned long long int uint64_t;
+typedef union
+{
+    struct
+    {
+        uint32_t leaf;
+        uint32_t subleaf;
+    };
+    uint64_t raw;
+} cpuid_config_leaf_subleaf_t;
+typedef struct
+{
+    cpuid_config_leaf_subleaf_t leaf_subleaf;
+} cpuid_lookup_t;
+extern const cpuid_lookup_t cpuid_lookup[68];
+const cpuid_lookup_t cpuid_lookup[68] = {
+ [10] = { .leaf_subleaf = {.leaf = 0x0, .subleaf = 0xffffffff}}
+};
+
+
+un v = { .leaf = 13 };
+
+typedef struct {
+  struct {};
+  struct {
+    long a;
+  };
+} b;
+
+b c = { .a = 0 };
+
+struct S1 {
+    struct {
+        int a;
+        int x;
+    };
+
+    struct {
+        int b;
+        int y;
+    };
+
+    struct {
+        int c;
+        int z;
+    };
+} s1 = {
+    .a = 1,
+    .b = 2,
+    .c = 3,
+    .x = 100,
+    .y = 101,
+    .z = 102
+};
+
+struct S2 {
+    union {
+        int a;
+        int b;
+    };
+
+    union {
+        struct {
+            int c;
+            int d;
+        };
+
+        struct {
+            int e;
+            int f;
+        };
+    };
+} s2 = {
+    .b = 100,
+    .c = 500,
+    .d = 600
+};
+
+struct S2 s2_2 = {
+    .a = 1,
+    .e = 2,
+    .f = 3
+};
+
+
+struct Complicated {
+    struct {
+        int a;
+    } s1;
+    struct {
+        int a;
+    };
+} c1 = {
+    .s1 = { .a = 1 },
+    .a = 2
+};
+
+
+
+int main() {
+  if(s2.b != 100 || s2.c != 500 || s2.d != 600) {
+    E(1);
+  }
+  if(s2_2.a != 1 || s2_2.e != 2 || s2_2.f != 3) {
+    E(2);
+  }
+  if(s1.a != 1 || s1.b != 2 || s1.c != 3 || s1.x != 100 || s1.y != 101 || s1.z != 102) {
+    E(3);
+  }
+  if(c.a != 0) {
+    E(4);
+  }
+  if(v.leaf != 13) {
+    E(5);
+  }
+  if(c1.a != 2 || c1.s1.a != 1) {
+    E(6);
+  }
+  SUCCESS;
+}
diff --git a/test/testcil.pl b/test/testcil.pl
index b4a23d806..8a3ab3940 100644
--- a/test/testcil.pl
+++ b/test/testcil.pl
@@ -173,6 +173,8 @@ sub addToGroup {
 addTest("test/apachebits");
 addTest("testrun/apachebuf");
 
+addTest("testrun/unioninit");
+
 addTest("testrun/apachefptr");
 addTest("testrun/asm1 _GNUCC=1");
 addTest("test/asm2 _GNUCC=1");