diff --git a/docs/internal-api.rst b/docs/internal-api.rst
index 5b157004..e542473b 100644
--- a/docs/internal-api.rst
+++ b/docs/internal-api.rst
@@ -42,10 +42,6 @@ Memory Management Functions and Macros
 
 Reductions and Related Functions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-.. doxygengroup:: nomp_reduction_ops
-   :project: libnomp
-   :content-only:
-
 .. doxygengroup:: nomp_reduction_utils
    :project: libnomp
    :content-only:
diff --git a/include/nomp-impl.h b/include/nomp-impl.h
index a8845fa4..31370ab6 100644
--- a/include/nomp-impl.h
+++ b/include/nomp-impl.h
@@ -80,6 +80,22 @@ typedef struct {
   void *ptr;
 } nomp_arg_t;
 
+/**
+ * @defgroup nomp_reduction_utils Reduction utilities
+ *
+ * @brief Utilities used to perform reduction operations.
+ */
+
+/**
+ * @ingroup nomp_reduction_utils
+ *
+ * @brief Enum for different reduction operations.
+ */
+typedef enum {
+  NOMP_SUM = 0, /*!< Sum reduction. */
+  NOMP_PROD = 1 /*!< Multiplication reduction.*/
+} nomp_reduction_op_t;
+
 /**
  * @ingroup nomp_internal_types
  *
@@ -103,7 +119,11 @@ typedef struct {
    */
   CVecBasic *sym_global, *sym_local;
   /**
-   * Map of variable names and their values use to evaluate
+   * Flag used to determine if the grid size should be evaluated or not.
+   */
+  int eval_grid;
+  /**
+   * Map of variable names and their values used to evaluate
    * the kernel launch parameters.
    */
   CMapBasicBasic *map;
@@ -112,12 +132,29 @@ typedef struct {
    * input changes).
    */
   size_t global[3], local[3], gws[3];
-  // Boolean flag to determine if the grid size should be evaluated or not.
-  int eval_grid;
-  // Pointer to keep track of backend specific data.
+  /**
+   * Pointer to keep track of backend specific data for the active backend.
+   */
   void *bptr;
-  // Reduction related metadata.
-  int redn_idx, redn_op, redn_type, redn_size;
+  /**
+   * Index of the deduction argument if one exists.
+   */
+  int redn_idx;
+  /**
+   * Reduction operation to be performed.
+   */
+  nomp_reduction_op_t redn_op;
+  /**
+   * Type of the reduction variable.
+   */
+  nomp_type_t redn_type;
+  /**
+   * Size of the reduction variable given by sizeof().
+   */
+  int redn_size;
+  /**
+   * Pointer to the reduction variable.
+   */
   void *redn_ptr;
 } nomp_prog_t;
 
@@ -234,6 +271,14 @@ int cuda_init(nomp_backend_t *backend, int platform, int device);
 
 int hip_init(nomp_backend_t *backend, int platform, int device);
 
+/**
+ * @ingroup nomp_reduction_utils
+ *
+ * @brief Perform residual host side reductions.
+ */
+int nomp_host_side_reduction(nomp_backend_t *bnd, nomp_prog_t *prg,
+                             nomp_mem_t *m);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/nomp-reduction.h b/include/nomp-reduction.h
deleted file mode 100644
index 85bf0eaf..00000000
--- a/include/nomp-reduction.h
+++ /dev/null
@@ -1,31 +0,0 @@
-#if !defined(_NOMP_REDUCTION_H_)
-#define _NOMP_REDUCTION_H_
-
-#include "nomp-impl.h"
-
-/**
- * @defgroup nomp_reduction_ops Reduction operations
- * @brief Defines reduction operations allowed in nomp kernels.
- */
-
-/**
- * @ingroup nomp_reduction_ops
- * @def NOMP_SUM
- * @brief Sum reduction operation.
- */
-#define NOMP_SUM 0
-/**
- * @ingroup nomp_reduction_ops
- * @def NOMP_PROD
- * @brief Product reduction operation.
- */
-#define NOMP_PROD 1
-
-/**
- * @defgroup nomp_reduction_utils Reduction utilities
- * @brief Perform host side reductions.
- */
-int nomp_host_side_reduction(nomp_backend_t *bnd, nomp_prog_t *prg,
-                             nomp_mem_t *m);
-
-#endif
diff --git a/src/nomp.c b/src/nomp.c
index 756df5f3..65fae10f 100644
--- a/src/nomp.c
+++ b/src/nomp.c
@@ -1,7 +1,6 @@
 #include "nomp-aux.h"
 #include "nomp-impl.h"
 #include "nomp-loopy.h"
-#include "nomp-reduction.h"
 
 static nomp_backend_t nomp;
 static int initialized = 0;
diff --git a/src/reduction.c b/src/reduction.c
index cba87a26..b48e4c3d 100644
--- a/src/reduction.c
+++ b/src/reduction.c
@@ -1,4 +1,4 @@
-#include "nomp-reduction.h"
+#include "nomp-impl.h"
 
 #define NOMP_DO_SUM(a, b) (a) += (b)
 #define NOMP_DO_PROD(a, b) (a) *= (b)