diff --git a/lib/arch/avx/codec.c b/lib/arch/avx/codec.c
index b80276b2..c9b9e181 100644
--- a/lib/arch/avx/codec.c
+++ b/lib/arch/avx/codec.c
@@ -33,7 +33,8 @@
 
 #endif	// HAVE_AVX
 
-BASE64_ENC_FUNCTION(avx)
+void
+base64_stream_encode_avx BASE64_ENC_PARAMS
 {
 #if HAVE_AVX
 	#include "../generic/enc_head.c"
@@ -54,7 +55,8 @@ BASE64_ENC_FUNCTION(avx)
 #endif
 }
 
-BASE64_DEC_FUNCTION(avx)
+int
+base64_stream_decode_avx BASE64_DEC_PARAMS
 {
 #if HAVE_AVX
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/avx2/codec.c b/lib/arch/avx2/codec.c
index eff56f18..638815a3 100644
--- a/lib/arch/avx2/codec.c
+++ b/lib/arch/avx2/codec.c
@@ -33,7 +33,8 @@
 
 #endif	// HAVE_AVX2
 
-BASE64_ENC_FUNCTION(avx2)
+void
+base64_stream_encode_avx2 BASE64_ENC_PARAMS
 {
 #if HAVE_AVX2
 	#include "../generic/enc_head.c"
@@ -44,7 +45,8 @@ BASE64_ENC_FUNCTION(avx2)
 #endif
 }
 
-BASE64_DEC_FUNCTION(avx2)
+int
+base64_stream_decode_avx2 BASE64_DEC_PARAMS
 {
 #if HAVE_AVX2
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/avx512/codec.c b/lib/arch/avx512/codec.c
index cd44a4e0..9667ae51 100644
--- a/lib/arch/avx512/codec.c
+++ b/lib/arch/avx512/codec.c
@@ -18,7 +18,8 @@
 
 #endif	// HAVE_AVX512
 
-BASE64_ENC_FUNCTION(avx512)
+void
+base64_stream_encode_avx512 BASE64_ENC_PARAMS
 {
 #if HAVE_AVX512
 	#include "../generic/enc_head.c"
@@ -30,7 +31,8 @@ BASE64_ENC_FUNCTION(avx512)
 }
 
 // Reuse AVX2 decoding. Not supporting AVX512 at present
-BASE64_DEC_FUNCTION(avx512)
+int
+base64_stream_decode_avx512 BASE64_DEC_PARAMS
 {
 #if HAVE_AVX512
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/generic/codec.c b/lib/arch/generic/codec.c
index 8dd5af23..303e6245 100644
--- a/lib/arch/generic/codec.c
+++ b/lib/arch/generic/codec.c
@@ -18,7 +18,8 @@
 #  include "32/dec_loop.c"
 #endif
 
-BASE64_ENC_FUNCTION(plain)
+void
+base64_stream_encode_plain BASE64_ENC_PARAMS
 {
 	#include "enc_head.c"
 #if BASE64_WORDSIZE == 32
@@ -29,7 +30,8 @@ BASE64_ENC_FUNCTION(plain)
 	#include "enc_tail.c"
 }
 
-BASE64_DEC_FUNCTION(plain)
+int
+base64_stream_decode_plain BASE64_DEC_PARAMS
 {
 	#include "dec_head.c"
 #if BASE64_WORDSIZE >= 32
diff --git a/lib/arch/neon32/codec.c b/lib/arch/neon32/codec.c
index 2727f3d9..70c80e48 100644
--- a/lib/arch/neon32/codec.c
+++ b/lib/arch/neon32/codec.c
@@ -52,7 +52,8 @@ vqtbl1q_u8 (const uint8x16_t lut, const uint8x16_t indices)
 // (48 bytes encode, 32 bytes decode) that we inline the
 // uint32 codec to stay performant on smaller inputs.
 
-BASE64_ENC_FUNCTION(neon32)
+void
+base64_stream_encode_neon32 BASE64_ENC_PARAMS
 {
 #ifdef BASE64_USE_NEON32
 	#include "../generic/enc_head.c"
@@ -64,7 +65,8 @@ BASE64_ENC_FUNCTION(neon32)
 #endif
 }
 
-BASE64_DEC_FUNCTION(neon32)
+int
+base64_stream_decode_neon32 BASE64_DEC_PARAMS
 {
 #ifdef BASE64_USE_NEON32
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/neon64/codec.c b/lib/arch/neon64/codec.c
index 2a22b937..f5cda63e 100644
--- a/lib/arch/neon64/codec.c
+++ b/lib/arch/neon64/codec.c
@@ -72,7 +72,8 @@ load_64byte_table (const uint8_t *p)
 // (48 bytes encode, 64 bytes decode) that we inline the
 // uint64 codec to stay performant on smaller inputs.
 
-BASE64_ENC_FUNCTION(neon64)
+void
+base64_stream_encode_neon64 BASE64_ENC_PARAMS
 {
 #ifdef BASE64_USE_NEON64
 	#include "../generic/enc_head.c"
@@ -84,7 +85,8 @@ BASE64_ENC_FUNCTION(neon64)
 #endif
 }
 
-BASE64_DEC_FUNCTION(neon64)
+int
+base64_stream_decode_neon64 BASE64_DEC_PARAMS
 {
 #ifdef BASE64_USE_NEON64
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/sse41/codec.c b/lib/arch/sse41/codec.c
index 33c675a1..54dae585 100644
--- a/lib/arch/sse41/codec.c
+++ b/lib/arch/sse41/codec.c
@@ -33,7 +33,8 @@
 
 #endif	// HAVE_SSE41
 
-BASE64_ENC_FUNCTION(sse41)
+void
+base64_stream_encode_sse41 BASE64_ENC_PARAMS
 {
 #if HAVE_SSE41
 	#include "../generic/enc_head.c"
@@ -44,7 +45,8 @@ BASE64_ENC_FUNCTION(sse41)
 #endif
 }
 
-BASE64_DEC_FUNCTION(sse41)
+int
+base64_stream_decode_sse41 BASE64_DEC_PARAMS
 {
 #if HAVE_SSE41
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/sse42/codec.c b/lib/arch/sse42/codec.c
index cdfec7e9..daa0b587 100644
--- a/lib/arch/sse42/codec.c
+++ b/lib/arch/sse42/codec.c
@@ -33,7 +33,8 @@
 
 #endif	// HAVE_SSE42
 
-BASE64_ENC_FUNCTION(sse42)
+void
+base64_stream_encode_sse42 BASE64_ENC_PARAMS
 {
 #if HAVE_SSE42
 	#include "../generic/enc_head.c"
@@ -44,7 +45,8 @@ BASE64_ENC_FUNCTION(sse42)
 #endif
 }
 
-BASE64_DEC_FUNCTION(sse42)
+int
+base64_stream_decode_sse42 BASE64_DEC_PARAMS
 {
 #if HAVE_SSE42
 	#include "../generic/dec_head.c"
diff --git a/lib/arch/ssse3/codec.c b/lib/arch/ssse3/codec.c
index 59b07a36..9d210e79 100644
--- a/lib/arch/ssse3/codec.c
+++ b/lib/arch/ssse3/codec.c
@@ -35,7 +35,8 @@
 
 #endif	// HAVE_SSSE3
 
-BASE64_ENC_FUNCTION(ssse3)
+void
+base64_stream_encode_ssse3 BASE64_ENC_PARAMS
 {
 #if HAVE_SSSE3
 	#include "../generic/enc_head.c"
@@ -46,7 +47,8 @@ BASE64_ENC_FUNCTION(ssse3)
 #endif
 }
 
-BASE64_DEC_FUNCTION(ssse3)
+int
+base64_stream_decode_ssse3 BASE64_DEC_PARAMS
 {
 #if HAVE_SSSE3
 	#include "../generic/dec_head.c"
diff --git a/lib/codec_choose.c b/lib/codec_choose.c
index abef3f2a..756f8015 100644
--- a/lib/codec_choose.c
+++ b/lib/codec_choose.c
@@ -78,9 +78,9 @@
 #endif
 
 // Function declarations:
-#define BASE64_CODEC_FUNCS(arch)	\
-	BASE64_ENC_FUNCTION(arch);	\
-	BASE64_DEC_FUNCTION(arch);	\
+#define BASE64_CODEC_FUNCS(arch)					\
+	extern void base64_stream_encode_ ## arch BASE64_ENC_PARAMS;	\
+	extern int  base64_stream_decode_ ## arch BASE64_DEC_PARAMS;
 
 BASE64_CODEC_FUNCS(avx512)
 BASE64_CODEC_FUNCS(avx2)
diff --git a/lib/codecs.h b/lib/codecs.h
index e2dddaea..f6af0e73 100644
--- a/lib/codecs.h
+++ b/lib/codecs.h
@@ -18,18 +18,6 @@
 	, size_t		*outlen		\
 	)
 
-// Function signature for encoding functions:
-#define BASE64_ENC_FUNCTION(arch)		\
-	void					\
-	base64_stream_encode_ ## arch		\
-	BASE64_ENC_PARAMS
-
-// Function signature for decoding functions:
-#define BASE64_DEC_FUNCTION(arch)		\
-	int					\
-	base64_stream_decode_ ## arch		\
-	BASE64_DEC_PARAMS
-
 // This function is used as a stub when a certain encoder is not compiled in.
 // It discards the inputs and returns zero output bytes.
 static inline void