diff --git a/c/examples/bobyqa/bobyqa_example.c b/c/examples/bobyqa/bobyqa_example.c
index 2879785af8..d871944961 100644
--- a/c/examples/bobyqa/bobyqa_example.c
+++ b/c/examples/bobyqa/bobyqa_example.c
@@ -18,16 +18,16 @@ int main(int argc, char * argv[])
   (void)argv;
   const int n = 2;
   double x0[2] = {0.0, 0.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.x0 = x0;
   problem.calfun = &fun;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_EXIT;
   options.rhoend= 1e-3;
   options.maxfun = 200*n;
-  prima_result result;
+  prima_result_t result;
   const int rc = prima_minimize(PRIMA_BOBYQA, &problem, &options, &result);
   printf("x*={%g, %g} rc=%d msg='%s' evals=%d\n", result.x[0], result.x[1], rc, result.message, result.nf);
   prima_free_problem(&problem);
diff --git a/c/examples/cobyla/cobyla_example.c b/c/examples/cobyla/cobyla_example.c
index 11ff544ff9..8053eabc2b 100644
--- a/c/examples/cobyla/cobyla_example.c
+++ b/c/examples/cobyla/cobyla_example.c
@@ -22,11 +22,11 @@ int main(int argc, char * argv[])
   (void)argv;
   const int n = 2;
   double x0[2] = {0.0, 0.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.calcfc = &fun;
   problem.x0 = x0;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_EXIT;
   options.rhoend= 1e-3;
@@ -46,7 +46,7 @@ int main(int argc, char * argv[])
   double xu[2] = {6.0, 6.0};
   problem.xl = xl;
   problem.xu = xu;
-  prima_result result;
+  prima_result_t result;
   const int rc = prima_minimize(PRIMA_COBYLA, &problem, &options, &result);
   printf("x*={%g, %g} f*=%g cstrv=%g nlconstr=%g rc=%d msg='%s' evals=%d\n", result.x[0], result.x[1], result.f, result.cstrv, result.nlconstr[0], rc, result.message, result.nf);
   prima_free_problem(&problem);
diff --git a/c/examples/lincoa/lincoa_example.c b/c/examples/lincoa/lincoa_example.c
index 55ed4861ce..e5aa89d05e 100644
--- a/c/examples/lincoa/lincoa_example.c
+++ b/c/examples/lincoa/lincoa_example.c
@@ -18,11 +18,11 @@ int main(int argc, char * argv[])
   (void)argv;
   const int n = 2;
   double x0[2] = {0.0, 0.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.calfun = &fun;
   problem.x0 = x0;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_EXIT;
   options.rhoend= 1e-3;
@@ -41,7 +41,7 @@ int main(int argc, char * argv[])
   double xu[2] = {6.0, 6.0};
   problem.xl = xl;
   problem.xu = xu;
-  prima_result result;
+  prima_result_t result;
   const int rc = prima_minimize(PRIMA_LINCOA, &problem, &options, &result);
   printf("x*={%g, %g} f*=%g cstrv=%g rc=%d msg='%s' evals=%d\n", result.x[0], result.x[1], result.f, result.cstrv, rc, result.message, result.nf);
   prima_free_problem(&problem);
diff --git a/c/examples/newuoa/newuoa_example.c b/c/examples/newuoa/newuoa_example.c
index 66c80d560e..00c4aa709b 100644
--- a/c/examples/newuoa/newuoa_example.c
+++ b/c/examples/newuoa/newuoa_example.c
@@ -18,16 +18,16 @@ int main(int argc, char * argv[])
   (void)argv;
   const int n = 2;
   double x0[2] = {0.0, 0.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.calfun = &fun;
   problem.x0 = x0;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_EXIT;
   options.rhoend= 1e-3;
   options.maxfun = 200*n;
-  prima_result result;
+  prima_result_t result;
   const int rc = prima_minimize(PRIMA_NEWUOA, &problem, &options, &result);
   printf("x*={%g, %g} rc=%d msg='%s' evals=%d\n", result.x[0], result.x[1], rc, result.message, result.nf);
   prima_free_problem(&problem);
diff --git a/c/examples/uobyqa/uobyqa_example.c b/c/examples/uobyqa/uobyqa_example.c
index 6e70afbc19..be53e87c21 100644
--- a/c/examples/uobyqa/uobyqa_example.c
+++ b/c/examples/uobyqa/uobyqa_example.c
@@ -18,16 +18,16 @@ int main(int argc, char * argv[])
   (void)argv;
   const int n = 2;
   double x0[2] = {0.0, 0.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.calfun = &fun;
   problem.x0 = x0;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_EXIT;
   options.rhoend= 1e-3;
   options.maxfun = 200*n;
-  prima_result result;
+  prima_result_t result;
   const int rc = prima_minimize(PRIMA_UOBYQA, &problem, &options, &result);
   printf("x*={%g, %g} rc=%d msg='%s' evals=%d\n", result.x[0], result.x[1], rc, result.message, result.nf);
   prima_free_problem(&problem);
diff --git a/c/include/prima/prima.h b/c/include/prima/prima.h
index 108cc82f5b..bb38c17961 100644
--- a/c/include/prima/prima.h
+++ b/c/include/prima/prima.h
@@ -31,7 +31,7 @@ typedef enum {
   PRIMA_MSG_EXIT = 1, /* Exit reasons */
   PRIMA_MSG_RHO = 2, /* Rho changes */
   PRIMA_MSG_FEVL = 3, /* The object/constraint functions get evaluated */
-} prima_message;
+} prima_message_t;
 
 /*
  * Possible return values
@@ -58,13 +58,13 @@ typedef enum
   PRIMA_NULL_X0 = 112,
   PRIMA_NULL_RESULT = 113,
   PRIMA_NULL_FUNCTION = 114,
-} prima_rc;
+} prima_rc_t;
 
 /*
  * Return code string
  */
 PRIMAC_API
-const char *prima_get_rc_string(int rc);
+const char *prima_get_rc_string(const prima_rc_t rc);
 
 /*
  * A function as required by solvers
@@ -77,8 +77,8 @@ const char *prima_get_rc_string(int rc);
  *          NaN values can be passed to signal evaluation errors
  *          only for cobyla
 */
-typedef void (*prima_obj)(const double x[], double *f, const void *data);
-typedef void (*prima_objcon)(const double x[], double *f, double constr[], const void *data);
+typedef void (*prima_obj_t)(const double x[], double *f, const void *data);
+typedef void (*prima_objcon_t)(const double x[], double *f, double constr[], const void *data);
 
 
 typedef struct {
@@ -92,7 +92,7 @@ typedef struct {
   // maximum number of function evaluations (default=-1 interpreted as 500*n)
   int maxfun;
 
-  // verbosity level, see the prima_message enum (default=PRIMA_MSG_NONE)
+  // verbosity level, see the prima_message_t enum (default=PRIMA_MSG_NONE)
   int iprint;
 
   // target function value; optimization stops when f <= ftarget for a feasible point (default=-inf)
@@ -105,11 +105,11 @@ typedef struct {
   // user-data, will be passed through the objective function callback
   void *data;
 
-} prima_options;
+} prima_options_t;
 
 /* Initialize problem */
 PRIMAC_API
-int prima_init_options(prima_options *options);
+int prima_init_options(prima_options_t *options);
 
 typedef struct {
 
@@ -117,10 +117,10 @@ typedef struct {
   int n;
 
   // objective function to minimize (not cobyla)
-  prima_obj calfun;
+  prima_obj_t calfun;
 
   // objective function to minimize with constraints (cobyla)
-  prima_objcon calcfc;
+  prima_objcon_t calcfc;
   
   // starting point
   double *x0;
@@ -157,15 +157,15 @@ typedef struct {
   // whether prima had to allocate nlconstr0 (private, do not use)
   int _allocated_nlconstr0;
   
-} prima_problem;
+} prima_problem_t;
 
 
 /* Initialize/free problem */
 PRIMAC_API
-int prima_init_problem(prima_problem *problem, int n);
+int prima_init_problem(prima_problem_t *problem, int n);
 
 PRIMAC_API
-int prima_free_problem(prima_problem *problem);
+int prima_free_problem(prima_problem_t *problem);
 
 
 typedef struct {
@@ -194,12 +194,12 @@ typedef struct {
   // error message
   const char *message;
 
-} prima_result;
+} prima_result_t;
 
 
 /* Free result after optimization */
 PRIMAC_API
-int prima_free_result(prima_result * result);
+int prima_free_result(prima_result_t * result);
 
 /*
  * Algorithm
@@ -211,7 +211,7 @@ typedef enum
   PRIMA_LINCOA,
   PRIMA_NEWUOA,
   PRIMA_UOBYQA
-} prima_algorithm;
+} prima_algorithm_t;
 
 
 /*
@@ -219,11 +219,11 @@ typedef enum
  * problem   : optimization problem (see prima_problem)
  * options   : optimization options (see prima_options)
  * result    : optimization result (see prima_result)
- * return    : see prima_rc enum for return codes
+ * return    : see prima_rc_t enum for return codes
  */
 
 PRIMAC_API
-int prima_minimize(prima_algorithm algorithm, prima_problem *problem, prima_options *options, prima_result *result);
+int prima_minimize(const prima_algorithm_t algorithm, prima_problem_t *problem, prima_options_t *options, prima_result_t *result);
 
 #ifdef __cplusplus
 }
diff --git a/c/prima.c b/c/prima.c
index 019e2ea64e..38d2d96127 100644
--- a/c/prima.c
+++ b/c/prima.c
@@ -8,11 +8,11 @@
 
 #define MAXFUN_DIM_DFT 500
 
-int prima_init_options(prima_options *options)
+int prima_init_options(prima_options_t *options)
 {
   if (options)
   {
-    memset(options, 0, sizeof(prima_options));
+    memset(options, 0, sizeof(prima_options_t));
     options->maxfun = -1;// interpreted as MAXFUN_DIM_DFT*n
     options->rhobeg = 1.0;
     options->rhoend = 1e-6;
@@ -25,11 +25,11 @@ int prima_init_options(prima_options *options)
     return PRIMA_NULL_OPTIONS;
 }
 
-int prima_init_problem(prima_problem *problem, int n)
+int prima_init_problem(prima_problem_t *problem, int n)
 {
   if (problem)
   {
-    memset(problem, 0, sizeof(prima_problem));
+    memset(problem, 0, sizeof(prima_problem_t));
     problem->n = n;
     problem->f0 = NAN;
     return 0;
@@ -39,26 +39,26 @@ int prima_init_problem(prima_problem *problem, int n)
 }
 
 /* implemented in fortran (*_c.f90) */
-int cobyla_c(const int m_nlcon, const prima_objcon calcfc, const void *data, const int n, double x[], double *f, double *cstrv, double nlconstr[],
+int cobyla_c(const int m_nlcon, const prima_objcon_t calcfc, const void *data, const int n, double x[], double *f, double *cstrv, double nlconstr[],
              const int m_ineq, const double Aineq[], const double bineq[],
              const int m_eq, const double Aeq[], const double beq[],
              const double xl[], const double xu[],
              double f0, const double nlconstr0[],
              int *nf, const double rhobeg, const double rhoend, const double ftarget, const int maxfun, const int iprint, int *info);
-int bobyqa_c(prima_obj calfun, const void *data, const int n, double x[], double *f, const double xl[], const double xu[],
+int bobyqa_c(prima_obj_t calfun, const void *data, const int n, double x[], double *f, const double xl[], const double xu[],
              int *nf, const double rhobeg, const double rhoend, const double ftarget, const int maxfun, const int npt, const int iprint, int *info);
-int newuoa_c(prima_obj calfun, const void *data, const int n, double x[], double *f,
+int newuoa_c(prima_obj_t calfun, const void *data, const int n, double x[], double *f,
              int *nf, const double rhobeg, const double rhoend, const double ftarget, const int maxfun, const int npt, const int iprint, int *info);
-int uobyqa_c(prima_obj calfun, const void *data, const int n, double x[], double *f,
+int uobyqa_c(prima_obj_t calfun, const void *data, const int n, double x[], double *f,
              int *nf, const double rhobeg, const double rhoend, const double ftarget, const int maxfun, const int iprint, int *info);
-int lincoa_c(prima_obj calfun, const void *data, const int n, double x[], double *f,
+int lincoa_c(prima_obj_t calfun, const void *data, const int n, double x[], double *f,
              double *cstrv,
              const int m_ineq, const double Aineq[], const double bineq[],
              const int m_eq, const double Aeq[], const double beq[],
              const double xl[], const double xu[],
              int *nf, const double rhobeg, const double rhoend, const double ftarget, const int maxfun, const int npt, const int iprint, int *info);
 
-int prima_check_problem(prima_problem *problem, prima_options *options, int alloc_bounds, int use_constr)
+int prima_check_problem(prima_problem_t *problem, prima_options_t *options, int alloc_bounds, int use_constr)
 {
   if (!problem)
     return PRIMA_NULL_PROBLEM;
@@ -93,7 +93,7 @@ int prima_check_problem(prima_problem *problem, prima_options *options, int allo
   return 0;
 }
 
-int prima_free_problem(prima_problem *problem)
+int prima_free_problem(prima_problem_t *problem)
 {
   if (problem)
   {
@@ -121,11 +121,11 @@ int prima_free_problem(prima_problem *problem)
     return PRIMA_NULL_PROBLEM;
 }
 
-int prima_init_result(prima_result *result, prima_problem *problem)
+int prima_init_result(prima_result_t *result, prima_problem_t *problem)
 {
   if (result)
   {
-    memset(result, 0, sizeof(prima_result));
+    memset(result, 0, sizeof(prima_result_t));
     result->f = 0.0;
     result->cstrv = 0.0;
     if (!problem)
@@ -142,7 +142,7 @@ int prima_init_result(prima_result *result, prima_problem *problem)
     return PRIMA_NULL_RESULT;
 }
 
-int prima_free_result(prima_result *result)
+int prima_free_result(prima_result_t *result)
 {
   if (result)
   {
@@ -159,7 +159,7 @@ int prima_free_result(prima_result *result)
 }
 
 /* these functions just call the fortran compatibility layer and return the status code */
-int prima_minimize(prima_algorithm algorithm, prima_problem *problem, prima_options *options, prima_result *result)
+int prima_minimize(const prima_algorithm_t algorithm, prima_problem_t *problem, prima_options_t *options, prima_result_t *result)
 {
   int alloc_bounds = (algorithm == PRIMA_COBYLA) || (algorithm == PRIMA_BOBYQA) || (algorithm == PRIMA_LINCOA);
   int use_constr = (algorithm == PRIMA_COBYLA);
@@ -235,7 +235,7 @@ int prima_minimize(prima_algorithm algorithm, prima_problem *problem, prima_opti
   return info;
 }
 
-const char *prima_get_rc_string(const int rc)
+const char *prima_get_rc_string(const prima_rc_t rc)
 {
   switch (rc)
   {
diff --git a/c/tests/data.c b/c/tests/data.c
index a806f23fcc..f72c7cfe6c 100644
--- a/c/tests/data.c
+++ b/c/tests/data.c
@@ -69,12 +69,12 @@ int main(int argc, char * argv[])
   double x0[] = {0, 0};
   double xl[] = {-6.0, -6.0};
   double xu[] = {6.0, 6.0};
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, n);
   problem.calcfc = &fun_con;
   problem.calfun = &fun;
   problem.x0 = x0;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_RHO;
   options.maxfun = 500*n;
@@ -90,8 +90,8 @@ int main(int argc, char * argv[])
   problem.bineq = bineq;
   problem.xl = xl;
   problem.xu = xu;
-  prima_result result;
-  int algorithm = 0;
+  prima_result_t result;
+  prima_algorithm_t algorithm = 0;
   if(strcmp(algo, "bobyqa") == 0)
   {
     algorithm = PRIMA_BOBYQA;
diff --git a/c/tests/stress.c b/c/tests/stress.c
index 65b02df3f4..cf25b9f201 100644
--- a/c/tests/stress.c
+++ b/c/tests/stress.c
@@ -83,12 +83,12 @@ int main(int argc, char * argv[])
   double x0[N_MAX];
   double xl[N_MAX];
   double xu[N_MAX];
-  prima_problem problem;
+  prima_problem_t problem;
   prima_init_problem(&problem, N_MAX);
   problem.x0 = x0;
   problem.calcfc = &fun_con;
   problem.calfun = &fun;
-  prima_options options;
+  prima_options_t options;
   prima_init_options(&options);
   options.iprint = PRIMA_MSG_RHO;
   options.maxfun = 500*N_MAX;
@@ -109,8 +109,8 @@ int main(int argc, char * argv[])
     xl[i] = -1.0;
     xu[i] = 1.0;
   }
-  int algorithm = 0;
-  prima_result result;
+  prima_algorithm_t algorithm = 0;
+  prima_result_t result;
   if(strcmp(algo, "bobyqa") == 0)
   {
     algorithm = PRIMA_BOBYQA;