diff --git a/include/cupdlpx_types.h b/include/cupdlpx_types.h
index d17a939..771c3e3 100644
--- a/include/cupdlpx_types.h
+++ b/include/cupdlpx_types.h
@@ -139,7 +139,7 @@ extern "C"
 		// treat abs(x) < zero_tolerance as zero
 		double zero_tolerance;
 
-		union
+		union MatrixData
 		{
 			struct
 			{					 // Dense (row-major)
diff --git a/src/mps_parser.c b/src/mps_parser.c
index d0b1d2e..756d741 100644
--- a/src/mps_parser.c
+++ b/src/mps_parser.c
@@ -157,7 +157,7 @@ static int namemap_put(NameMap *map, const char *name)
 typedef struct
 {
     bool is_gz;
-    union
+    union FileHandle
     {
         gzFile gz_f;
         FILE *f;