diff --git a/Makefile b/Makefile
index 015fae11a..0deebbff8 100644
--- a/Makefile
+++ b/Makefile
@@ -210,6 +210,7 @@ INC := -Iinclude -Iinclude/libc -Isrc -I$(BUILD_DIR) -I. -I$(EXTRACTED_DIR)
 
 # Check code syntax with host compiler
 CHECK_WARNINGS := -Wall -Wextra -Wno-format-security -Wno-unknown-pragmas -Wno-unused-parameter -Wno-unused-variable -Wno-missing-braces
+CHECK_WARNINGS += -Werror=implicit-function-declaration -Werror=incompatible-pointer-types -Werror=int-conversion
 
 # The `cpp` command behaves differently on macOS (it behaves as if
 # `-traditional-cpp` was passed) so we use `gcc -E` instead.
diff --git a/include/compression.h b/include/compression.h
index 3a068285b..a530646da 100644
--- a/include/compression.h
+++ b/include/compression.h
@@ -2,6 +2,7 @@
 #define COMPRESSION_H
 
 #include "ultra64.h"
+#include "z64dma.h"
 
 void* Yaz0_FirstDMA(void);
 void* Yaz0_NextDMA(u8* curSrcPos);
diff --git a/src/code/sys_math3d_draw.c b/src/code/sys_math3d_draw.c
index 8b1d42b83..4c31d6500 100644
--- a/src/code/sys_math3d_draw.c
+++ b/src/code/sys_math3d_draw.c
@@ -1,4 +1,5 @@
 #include "z64.h"
+#include "functions.h"
 
 #if IS_DEBUG
 void Math3D_VtxF2L(Vtx* r, Vec3f* v) {