diff --git a/tests/31-set-of-OK.asn1.-P b/tests/31-set-of-OK.asn1.-P
index c7d8f0b..03cd72d 100644
--- a/tests/31-set-of-OK.asn1.-P
+++ b/tests/31-set-of-OK.asn1.-P
@@ -203,7 +203,7 @@
 	 */
 	struct other {
 		other_PR present;
-		union {
+		union Stuff__other_u {
 			INTEGER_t	 a;
 			INTEGER_t	 b;
 		} choice;
diff --git a/tests/42-real-life-OK.asn1.-PR b/tests/42-real-life-OK.asn1.-PR
index 09aed56..f0aef03 100644
--- a/tests/42-real-life-OK.asn1.-PR
+++ b/tests/42-real-life-OK.asn1.-PR
@@ -339,7 +339,7 @@
 
 typedef struct VariablePart {
 	VariablePart_PR present;
-	union {
+	union VariablePart_u {
 		struct vset {
 			A_SET_OF(VisibleString_t) list;
 			
diff --git a/tests/43-recursion-OK.asn1.-P b/tests/43-recursion-OK.asn1.-P
index 02135e7..6d83f61 100644
--- a/tests/43-recursion-OK.asn1.-P
+++ b/tests/43-recursion-OK.asn1.-P
@@ -220,7 +220,7 @@
 
 typedef struct Choice_1 {
 	Choice_1_PR present;
-	union {
+	union Choice_1_u {
 		struct Choice_1	*and;
 		struct or {
 			A_SET_OF(struct Choice_1) list;
diff --git a/tests/44-choice-in-sequence-OK.asn1.-P b/tests/44-choice-in-sequence-OK.asn1.-P
index 936fbe8..bd9dd8d 100644
--- a/tests/44-choice-in-sequence-OK.asn1.-P
+++ b/tests/44-choice-in-sequence-OK.asn1.-P
@@ -31,12 +31,12 @@
 	NULL_t	 a;
 	struct b {
 		b_PR present;
-		union {
+		union T__b_u {
 			NULL_t	 c;
 			NULL_t	 d;
 			struct e {
 				e_PR present;
-				union {
+				union T__b__e_u {
 					NULL_t	 f;
 					NULL_t	 g;
 				} choice;
@@ -46,7 +46,7 @@
 			} e;
 			struct h {
 				h_PR present;
-				union {
+				union T__b__h_u {
 					NULL_t	 i;
 					NULL_t	 j;
 				} choice;
diff --git a/tests/47-set-ext-OK.asn1.-P b/tests/47-set-ext-OK.asn1.-P
index 660048b..72d605b 100644
--- a/tests/47-set-ext-OK.asn1.-P
+++ b/tests/47-set-ext-OK.asn1.-P
@@ -196,7 +196,7 @@
 
 typedef struct T3 {
 	T3_PR present;
-	union {
+	union T3_u {
 		INTEGER_t	 i;
 		/*
 		 * This type is extensible,
@@ -273,7 +273,7 @@
 
 typedef struct T4 {
 	T4_PR present;
-	union {
+	union T4_u {
 		INTEGER_t	 i;
 		/*
 		 * This type is extensible,
diff --git a/tests/59-choice-extended-OK.asn1.-P b/tests/59-choice-extended-OK.asn1.-P
index 391cbca..f7f8a2c 100644
--- a/tests/59-choice-extended-OK.asn1.-P
+++ b/tests/59-choice-extended-OK.asn1.-P
@@ -23,7 +23,7 @@
 
 typedef struct Choice {
 	Choice_PR present;
-	union {
+	union Choice_u {
 		INTEGER_t	 a;
 		/*
 		 * This type is extensible,
diff --git a/tests/70-xer-test-OK.asn1.-P b/tests/70-xer-test-OK.asn1.-P
index 26c651a..74c0b1d 100644
--- a/tests/70-xer-test-OK.asn1.-P
+++ b/tests/70-xer-test-OK.asn1.-P
@@ -34,7 +34,7 @@
 
 typedef struct PDU {
 	PDU_PR present;
-	union {
+	union PDU_u {
 		Sequence_t	 sequence;
 		Set_t	 set;
 		SetOf_t	 setOf;
diff --git a/tests/72-same-names-OK.asn1.-P b/tests/72-same-names-OK.asn1.-P
index 3433fd1..1e8b3e3 100644
--- a/tests/72-same-names-OK.asn1.-P
+++ b/tests/72-same-names-OK.asn1.-P
@@ -141,7 +141,7 @@
 typedef struct Type1 {
 	struct one_name {
 		one_name_PR present;
-		union {
+		union Type1__one_name_u {
 			struct another_name {
 				INTEGER_t	 a;
 				INTEGER_t	 b;
@@ -340,7 +340,7 @@
 
 typedef struct Type2 {
 	Type2_PR present;
-	union {
+	union Type2_u {
 		struct one_name {
 			struct another_name {
 				BIT_STRING_t	 a;
diff --git a/tests/84-param-tags-OK.asn1.-P b/tests/84-param-tags-OK.asn1.-P
index 282dfe4..b45977b 100644
--- a/tests/84-param-tags-OK.asn1.-P
+++ b/tests/84-param-tags-OK.asn1.-P
@@ -18,7 +18,7 @@
 
 typedef struct TestChoice {
 	TestChoice_PR present;
-	union {
+	union TestChoice_u {
 		struct type1 {
 			long	*common	/* DEFAULT 0 */;
 			
@@ -233,7 +233,7 @@
 
 typedef struct AutoChoice {
 	AutoChoice_PR present;
-	union {
+	union AutoChoice_u {
 		struct type1 {
 			long	 common;
 			
diff --git a/tests/89-bit-string-enum-OK.asn1.-P b/tests/89-bit-string-enum-OK.asn1.-P
index 0ab33be..3cd1f35 100644
--- a/tests/89-bit-string-enum-OK.asn1.-P
+++ b/tests/89-bit-string-enum-OK.asn1.-P
@@ -19,7 +19,7 @@
 
 typedef struct T {
 	T_PR present;
-	union {
+	union T_u {
 		BIT_STRING_t	 bs;
 	} choice;
 	
diff --git a/tests/89-bit-string-enum-OK.asn1.-Pfcompound-names b/tests/89-bit-string-enum-OK.asn1.-Pfcompound-names
index 1fe136a..9ac69a2 100644
--- a/tests/89-bit-string-enum-OK.asn1.-Pfcompound-names
+++ b/tests/89-bit-string-enum-OK.asn1.-Pfcompound-names
@@ -19,7 +19,7 @@
 
 typedef struct T {
 	T_PR present;
-	union {
+	union T_u {
 		BIT_STRING_t	 bs;
 	} choice;