diff --git a/gibbon-rts/Makefile b/gibbon-rts/Makefile
index d76b8ccde..75ee35aff 100644
--- a/gibbon-rts/Makefile
+++ b/gibbon-rts/Makefile
@@ -28,7 +28,7 @@
 
 CC        := gcc
 AR        := gcc-ar
-CFLAGS    := -Wall -Wextra -Wpedantic -Wshadow -std=gnu11 -flto
+CFLAGS    := -Wall -Wextra -Wpedantic -Wshadow -Werror -std=gnu11 -flto
 RSC       := cargo
 RSFLAGS   := -v
 VERBOSITY := 1
diff --git a/gibbon-rts/rts-c/gibbon_rts.c b/gibbon-rts/rts-c/gibbon_rts.c
index e0a0f5c5f..8fcc6c989 100644
--- a/gibbon-rts/rts-c/gibbon_rts.c
+++ b/gibbon-rts/rts-c/gibbon_rts.c
@@ -145,7 +145,7 @@ GibSym gib_read_gensym_counter(void)
 #ifdef _GIBBON_POINTER
 
 #ifdef _GIBBON_BUMPALLOC_HEAP
-#warning "Using bump allocator."
+#pragma message "Using bump allocator."
 
 static __thread char *gib_global_ptr_bumpalloc_heap_ptr = (char *) NULL;
 static __thread char *gib_global_ptr_bumpalloc_heap_ptr_end = (char *) NULL;
@@ -706,7 +706,7 @@ double gib_sum_timing_array(GibVector *times)
 
 #ifdef _GIBBON_BUMPALLOC_LISTS
 // #define _GIBBON_DEBUG
-#warning "Using bump allocator."
+#pragma message "Using bump allocator."
 
 static __thread char *gib_global_list_bumpalloc_heap_ptr = (char *) NULL;
 static __thread char *gib_global_list_bumpalloc_heap_ptr_end = (char *) NULL;
@@ -1036,26 +1036,26 @@ void gib_print_gc_config(void) {
     printf("C config\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
 
 #if defined _GIBBON_GENGC && _GIBBON_GENGC == 0
-    #warning "Generational GC is disabled."
+    #pragma message "Generational GC is disabled."
     printf("Generational GC is disabled.\n");
 #else
-    #warning "Generational GC is enabled."
+    #pragma message "Generational GC is enabled."
     printf("Generational GC is enabled.\n");
 #endif
 
 #if defined _GIBBON_EAGER_PROMOTION && _GIBBON_EAGER_PROMOTION == 0
-    #warning "Eager promotion is disabled."
+    #pragma message "Eager promotion is disabled."
     printf("Eager promotion is disabled.\n");
 #else
-    #warning "Eager promotion is enabled."
+    #pragma message "Eager promotion is enabled."
     printf("Eager promotion is enabled.\n");
 #endif
 
 #if defined _GIBBON_SIMPLE_WRITE_BARRIER && _GIBBON_SIMPLE_WRITE_BARRIER == 0
-    #warning "Simple write barrier is disabled."
+    #pragma message "Simple write barrier is disabled."
     printf("Simple write barrier is disabled.\n");
 #else
-    #warning "Simple write barrier is enabled."
+    #pragma message "Simple write barrier is enabled."
     printf("Simple write barrier is enabled.\n");
 #endif
 
@@ -1316,8 +1316,8 @@ void gib_print_global_region_count(void)
  */
 
 // Initialize nurseries, shadow stacks and generations.
-static void gib_storage_initialize(void);
-static void gib_storage_free(void);
+UNUSED_IN_POINTER_BAK static void gib_storage_initialize(void);
+UNUSED_IN_POINTER_BAK static void gib_storage_free(void);
 static void gib_nursery_initialize(GibNursery *nursery, size_t nsize);
 static void gib_nursery_free(GibNursery *nursery);
 static void gib_oldgen_initialize(GibOldgen *oldgen);
@@ -1328,7 +1328,7 @@ static void gib_gc_stats_initialize(GibGcStats *stats);
 static void gib_gc_stats_free(GibGcStats *stats);
 
 // Initialize nurseries, shadow stacks and generations.
-static void gib_storage_initialize(void)
+UNUSED_IN_POINTER_BAK static void gib_storage_initialize(void)
 {
     if (gib_storage_initialized) {
         return;
@@ -1339,7 +1339,7 @@ static void gib_storage_initialize(void)
     gib_gc_stats_initialize(gib_global_gc_stats);
 
     // Initialize nurseries.
-    int n;
+    uint64_t n;
     gib_global_nurseries = (GibNursery *) gib_alloc(gib_global_num_threads *
                                                     sizeof(GibNursery));
     for (n = 0; n < gib_global_num_threads; n++) {
@@ -1351,7 +1351,7 @@ static void gib_storage_initialize(void)
     gib_oldgen_initialize(gib_global_oldgen);
 
     // Initialize shadow stacks.
-    int ss;
+    uint64_t ss;
     gib_global_read_shadowstacks =
             (GibShadowstack *) gib_alloc(gib_global_num_threads *
                                          sizeof(GibShadowstack));
@@ -1368,14 +1368,14 @@ static void gib_storage_initialize(void)
     return;
 }
 
-static void gib_storage_free(void)
+UNUSED_IN_POINTER_BAK static void gib_storage_free(void)
 {
     if (!gib_storage_initialized) {
         return;
     }
 
     // Free nurseries.
-    int n;
+    uint64_t n;
     for (n = 0; n < gib_global_num_threads; n++) {
         gib_nursery_free(&(gib_global_nurseries[n]));
      }
@@ -1386,7 +1386,7 @@ static void gib_storage_free(void)
     gib_free(gib_global_oldgen);
 
     // Free shadow-stacks.
-    int ss;
+    uint64_t ss;
     for (ss = 0; ss < gib_global_num_threads; ss++) {
         gib_shadowstack_free(&(gib_global_read_shadowstacks[ss]));
         gib_shadowstack_free(&(gib_global_write_shadowstacks[ss]));
@@ -1599,6 +1599,7 @@ static void gib_gc_stats_free(GibGcStats *stats)
     gib_free(stats);
 }
 
+#ifdef _GIBBON_GCSTATS
 static void gib_gc_stats_print(GibGcStats *stats)
 {
     printf("\nGC statistics\n----------------------------------------\n");
@@ -1652,6 +1653,7 @@ static void gib_gc_stats_print(GibGcStats *stats)
     printf("Skipover env inserts:\t\t %ld\n", stats->skipover_env_inserts);
     printf("Root set size:\t\t\t %ld\n", stats->rootset_size);
 }
+#endif // ifdef _GIBBON_GCSTATS
 
 
 /*
@@ -1929,7 +1931,7 @@ int gib_init(int argc, char **argv)
     }
 #endif
 
-    int got_numargs = argc; // How many numeric arguments have we got.
+    // int got_numargs = argc; // How many numeric arguments have we got.
 
     int i;
     for (i = 1; i < argc; ++i)
diff --git a/gibbon-rts/rts-c/gibbon_rts.h b/gibbon-rts/rts-c/gibbon_rts.h
index 6b7575a9b..68bbdbc3f 100644
--- a/gibbon-rts/rts-c/gibbon_rts.h
+++ b/gibbon-rts/rts-c/gibbon_rts.h
@@ -80,8 +80,16 @@ typedef uint64_t GibThreadId;
 #define ATTR_ALWAYS_INLINE __attribute__((always_inline))
 #define ATTR_HOT __attribute__((hot))
 
+#ifdef _GIBBON_POINTER
+#define UNUSED_IN_POINTER_BAK __attribute__((unused))
+#else
+#define UNUSED_IN_POINTER_BAK
+#endif
+
 #define LIKELY(x) __builtin_expect((bool) (x), 1)
 #define UNLIKELY(x) __builtin_expect((bool) (x), 0)
+#define IGNORE(x) (void) (x)
+
 
 /*
  * Inlining macros taken from GHC:
@@ -1069,9 +1077,9 @@ INLINE_HEADER void gib_indirection_barrier(
 {
 
 #if defined _GIBBON_SIMPLE_WRITE_BARRIER && _GIBBON_SIMPLE_WRITE_BARRIER == 1
-    #warning "Simple write barrier is enabled."
+    #pragma message "Simple write barrier is enabled."
 #else
-    #warning "Simple write barrier is disabled."
+    #pragma message "Simple write barrier is disabled."
     {
         // Optimization: don't create long chains of indirection pointers.
         GibPackedTag pointed_to_tag = *(GibPackedTag *) to;
@@ -1105,6 +1113,7 @@ INLINE_HEADER void gib_indirection_barrier(
     // old-to-old indirections.
 
 #if defined _GIBBON_GENGC && _GIBBON_GENGC == 0
+    IGNORE(datatype);
     gib_add_old_to_old_indirection(from_footer, to_footer);
     return;
 #else
diff --git a/gibbon-rts/rts-ng/src/gc.rs b/gibbon-rts/rts-ng/src/gc.rs
index 8f5e8648f..ee995f8fe 100644
--- a/gibbon-rts/rts-ng/src/gc.rs
+++ b/gibbon-rts/rts-ng/src/gc.rs
@@ -147,8 +147,9 @@ pub fn cleanup(
                 (*((*oldgen).old_zct)).insert((*footer).reg_info);
             }
         }
-        for reg_info in (*((*oldgen).old_zct)).drain() {
-            // free_region((*reg_info).first_chunk_footer, null_mut())?;
+        for _reg_info in (*((*oldgen).old_zct)).drain() {
+            // Enable this again after ensuring that everything works.
+            // // free_region((*reg_info).first_chunk_footer, null_mut())?;
         }
     }
     // Free ZCTs associated with the oldest generation.
diff --git a/gibbon-rts/rts-ng/src/lib.rs b/gibbon-rts/rts-ng/src/lib.rs
index e3b3feed3..109f985cf 100644
--- a/gibbon-rts/rts-ng/src/lib.rs
+++ b/gibbon-rts/rts-ng/src/lib.rs
@@ -1,5 +1,9 @@
 //! Next generation runtime system for the Gibbon compiler.
 
+// Erroring on every warning is OK for now, but can be refined in the future:
+// https://rust-unofficial.github.io/patterns/anti_patterns/deny-warnings.html
+#![deny(warnings)]
+
 pub use ffi::c::*;
 pub use ffi::rs::*;
 pub use gc::ValueStats;