diff --git a/test/h5b_read.c b/test/h5b_read.c
index 7bdbacd..820da2c 100644
--- a/test/h5b_read.c
+++ b/test/h5b_read.c
@@ -60,7 +60,6 @@ test_read_data64(h5_file_t file, int step)
 	extern h5_size_t layout[6];
 
 	int i,t;
-	int rank, nprocs;
 	h5_err_t status;
 	h5_int64_t val, type[2];
 	char name[4];
@@ -84,11 +83,9 @@ test_read_data64(h5_file_t file, int step)
 	TEST("Verifying dataset info");
 
 #if defined(PARALLEL_IO)
+	int rank, nprocs;
 	MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 	MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
-#else
-	nprocs = 1;
-	rank = 2;
 #endif
 
 	status = H5SetStep(file, step);
diff --git a/test/h5b_test.c b/test/h5b_test.c
index 0dadc77..5f67a54 100644
--- a/test/h5b_test.c
+++ b/test/h5b_test.c
@@ -18,6 +18,7 @@ void h5b_test_write2(void);
 void h5b_test_read1(void);
 void h5b_test_read2(void);
 
+#ifdef PARALLEL_IO
 static int
 _nth_root_int_divisor (const int m, const int n)
 {
@@ -33,6 +34,7 @@ _nth_root_int_divisor (const int m, const int n)
 
 	return i;
 }
+#endif
 
 int main(int argc, char **argv)
 {
diff --git a/test/h5b_write.c b/test/h5b_write.c
index cfccf27..8f66b38 100644
--- a/test/h5b_write.c
+++ b/test/h5b_write.c
@@ -108,8 +108,6 @@ test_write_data64(h5_file_t file, int step)
 static void
 test_write_data32(h5_file_t file, int step)
 {
-	extern h5_size_t grid[3];
-
 	int i,j,k,t;
 	h5_int64_t status, val;
 
@@ -152,6 +150,8 @@ test_write_data32(h5_file_t file, int step)
 		if (val == 0) test_write_field_attribs(file, "e", t);
 
 #if defined(PARALLEL_IO)
+		extern h5_size_t grid[3];
+
 		status = H5Block3dSetGrid(file, grid[0], grid[1], grid[2]);
 		RETURN(status, H5_SUCCESS, "H5Block3dSetGrid");
 
diff --git a/test/h5u_write.c b/test/h5u_write.c
index 0a3106e..ef73097 100644
--- a/test/h5u_write.c
+++ b/test/h5u_write.c
@@ -195,7 +195,6 @@ test_write_data32(h5_file_t file, int nparticles, int step)
 	int i,t;
 	h5_err_t status;
 	h5_size_t val;
-	int rank, nprocs;
 
 	float *x,*y,*z;
 	float *px,*py,*pz;
@@ -213,11 +212,11 @@ test_write_data32(h5_file_t file, int nparticles, int step)
 	RETURN(status, H5_SUCCESS, "H5PartSetNumParticles");
 
 #if defined(PARALLEL_IO)
+	int rank, nprocs;
 	MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 	MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
 #else
-	rank = 0;
-	nprocs = 1;
+	int rank = 0;
 #endif
 
 	TEST("Writing 32-bit data");
diff --git a/test/testframe.h b/test/testframe.h
index 3633c64..61089f9 100644
--- a/test/testframe.h
+++ b/test/testframe.h
@@ -8,10 +8,6 @@
 
 #include <H5hut.h>
 
-#ifndef PARALLEL_IO
-#define MPI_COMM_WORLD 0
-#endif
-
 /*
  * Predefined test verbosity levels.
  *