diff --git a/NEWS b/NEWS
index 68539d759..b3c2613fe 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,7 @@ perf: substantially decreased memory usage in Multi-threading mode, thanks to re
 perf: Multi-threading supports up to 256 threads. Cap at 256 when more are requested (#760)
 build: fix Visual compilation for non x86/x64 targets, reported by Greg Slazinski (#718)
 API exp : breaking change : ZSTD_getframeHeader() provides more information
+API exp : breaking change : pinned down values of error codes
 
 v1.3.0
 cli : new : `--list` command, by Paul Cruz
diff --git a/lib/common/error_private.c b/lib/common/error_private.c
index 2d752cd23..c3a386214 100644
--- a/lib/common/error_private.c
+++ b/lib/common/error_private.c
@@ -20,19 +20,17 @@ const char* ERR_getErrorString(ERR_enum code)
     case PREFIX(GENERIC):  return "Error (generic)";
     case PREFIX(prefix_unknown): return "Unknown frame descriptor";
     case PREFIX(version_unsupported): return "Version not supported";
-    case PREFIX(parameter_unknown): return "Unknown parameter type";
     case PREFIX(frameParameter_unsupported): return "Unsupported frame parameter";
-    case PREFIX(frameParameter_unsupportedBy32bits): return "Frame parameter unsupported in 32-bits mode";
     case PREFIX(frameParameter_windowTooLarge): return "Frame requires too much memory for decoding";
-    case PREFIX(compressionParameter_unsupported): return "Compression parameter is not supported";
-    case PREFIX(compressionParameter_outOfBound): return "Compression parameter is out of bound";
+    case PREFIX(corruption_detected): return "Corrupted block detected";
+    case PREFIX(checksum_wrong): return "Restored data doesn't match checksum";
+    case PREFIX(parameter_unsupported): return "Unsupported parameter";
+    case PREFIX(parameter_outOfBound): return "Parameter is out of bound";
     case PREFIX(init_missing): return "Context should be init first";
     case PREFIX(memory_allocation): return "Allocation error : not enough memory";
     case PREFIX(stage_wrong): return "Operation not authorized at current processing stage";
     case PREFIX(dstSize_tooSmall): return "Destination buffer is too small";
     case PREFIX(srcSize_wrong): return "Src size is incorrect";
-    case PREFIX(corruption_detected): return "Corrupted block detected";
-    case PREFIX(checksum_wrong): return "Restored data doesn't match checksum";
     case PREFIX(tableLog_tooLarge): return "tableLog requires too much memory : unsupported";
     case PREFIX(maxSymbolValue_tooLarge): return "Unsupported max Symbol Value : too large";
     case PREFIX(maxSymbolValue_tooSmall): return "Specified maxSymbolValue is too small";
diff --git a/lib/common/zstd_errors.h b/lib/common/zstd_errors.h
index 19f1597aa..a645a9e8e 100644
--- a/lib/common/zstd_errors.h
+++ b/lib/common/zstd_errors.h
@@ -37,43 +37,41 @@ extern "C" {
 /*-****************************************
  *  error codes list
  *  note : this API is still considered unstable
- *         it should not be used with a dynamic library
+ *         and shall not be used with a dynamic library.
  *         only static linking is allowed
  ******************************************/
 typedef enum {
-  ZSTD_error_no_error,
-  ZSTD_error_GENERIC,
-  ZSTD_error_prefix_unknown,
-  ZSTD_error_version_unsupported,
-  ZSTD_error_parameter_unknown,
-  ZSTD_error_frameParameter_unsupported,
-  ZSTD_error_frameParameter_unsupportedBy32bits,
-  ZSTD_error_frameParameter_windowTooLarge,
-  ZSTD_error_compressionParameter_unsupported,
-  ZSTD_error_compressionParameter_outOfBound,
-  ZSTD_error_init_missing,
-  ZSTD_error_memory_allocation,
-  ZSTD_error_stage_wrong,
-  ZSTD_error_dstSize_tooSmall,
-  ZSTD_error_srcSize_wrong,
-  ZSTD_error_corruption_detected,
-  ZSTD_error_checksum_wrong,
-  ZSTD_error_tableLog_tooLarge,
-  ZSTD_error_maxSymbolValue_tooLarge,
-  ZSTD_error_maxSymbolValue_tooSmall,
-  ZSTD_error_dictionary_corrupted,
-  ZSTD_error_dictionary_wrong,
-  ZSTD_error_dictionaryCreation_failed,
-  ZSTD_error_frameIndex_tooLarge,
-  ZSTD_error_seekableIO,
-  ZSTD_error_maxCode
+  ZSTD_error_no_error = 0,
+  ZSTD_error_GENERIC  = 1,
+  ZSTD_error_prefix_unknown                = 10,
+  ZSTD_error_version_unsupported           = 12,
+  ZSTD_error_frameParameter_unsupported    = 14,
+  ZSTD_error_frameParameter_windowTooLarge = 16,
+  ZSTD_error_corruption_detected = 20,
+  ZSTD_error_checksum_wrong      = 22,
+  ZSTD_error_dictionary_corrupted      = 30,
+  ZSTD_error_dictionary_wrong          = 32,
+  ZSTD_error_dictionaryCreation_failed = 34,
+  ZSTD_error_parameter_unsupported   = 40,
+  ZSTD_error_parameter_outOfBound    = 42,
+  ZSTD_error_tableLog_tooLarge       = 44,
+  ZSTD_error_maxSymbolValue_tooLarge = 46,
+  ZSTD_error_maxSymbolValue_tooSmall = 48,
+  ZSTD_error_stage_wrong       = 60,
+  ZSTD_error_init_missing      = 62,
+  ZSTD_error_memory_allocation = 64,
+  ZSTD_error_dstSize_tooSmall = 70,
+  ZSTD_error_srcSize_wrong    = 72,
+  ZSTD_error_frameIndex_tooLarge = 100,
+  ZSTD_error_seekableIO          = 102,
+  ZSTD_error_maxCode = 120  /* never EVER use this value directly, it may change in future versions! Use ZSTD_isError() instead */
 } ZSTD_ErrorCode;
 
 /*! ZSTD_getErrorCode() :
     convert a `size_t` function result into a `ZSTD_ErrorCode` enum type,
     which can be used to compare with enum list published above */
 ZSTDERRORLIB_API ZSTD_ErrorCode ZSTD_getErrorCode(size_t functionResult);
-ZSTDERRORLIB_API const char* ZSTD_getErrorString(ZSTD_ErrorCode code);
+ZSTDERRORLIB_API const char* ZSTD_getErrorString(ZSTD_ErrorCode code);   /**< Same as ZSTD_getErrorName, but using a `ZSTD_ErrorCode` enum argument */
 
 
 #if defined (__cplusplus)
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index b362a1919..4ccb7ce6b 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -214,7 +214,7 @@ size_t ZSTD_setCCtxParameter(ZSTD_CCtx* cctx, ZSTD_CCtxParameter param, unsigned
     ZSTD_STATIC_ASSERT(ZSTD_dm_auto==0);
     ZSTD_STATIC_ASSERT(ZSTD_dm_rawContent==1);
     case ZSTD_p_forceRawDict : cctx->dictMode = (ZSTD_dictMode_e)(value>0); return 0;
-    default: return ERROR(parameter_unknown);
+    default: return ERROR(parameter_unsupported);
     }
 }
 
@@ -228,9 +228,9 @@ static void ZSTD_cLevelToCParams(ZSTD_CCtx* cctx)
     cctx->compressionLevel = ZSTD_CLEVEL_CUSTOM;
 }
 
-#define CLAMPCHECK(val,min,max) {                       \
-    if (((val)<(min)) | ((val)>(max))) {                \
-        return ERROR(compressionParameter_outOfBound);  \
+#define CLAMPCHECK(val,min,max) {            \
+    if (((val)<(min)) | ((val)>(max))) {     \
+        return ERROR(parameter_outOfBound);  \
 }   }
 
 size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value)
@@ -326,7 +326,7 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned v
         /* restrict dictionary mode, to "rawContent" or "fullDict" only */
         ZSTD_STATIC_ASSERT((U32)ZSTD_dm_fullDict > (U32)ZSTD_dm_rawContent);
         if (value > (unsigned)ZSTD_dm_fullDict)
-            return ERROR(compressionParameter_outOfBound);
+            return ERROR(parameter_outOfBound);
         cctx->dictMode = (ZSTD_dictMode_e)value;
         return 0;
 
@@ -347,11 +347,11 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned v
         if (value==0) return 0;
         DEBUGLOG(5, " setting nbThreads : %u", value);
 #ifndef ZSTD_MULTITHREAD
-        if (value > 1) return ERROR(compressionParameter_unsupported);
+        if (value > 1) return ERROR(parameter_unsupported);
 #endif
         if ((value>1) && (cctx->nbThreads != value)) {
             if (cctx->staticSize)  /* MT not compatible with static alloc */
-                return ERROR(compressionParameter_unsupported);
+                return ERROR(parameter_unsupported);
             ZSTDMT_freeCCtx(cctx->mtctx);
             cctx->nbThreads = 1;
             cctx->mtctx = ZSTDMT_createCCtx_advanced(value, cctx->customMem);
@@ -361,17 +361,17 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned v
         return 0;
 
     case ZSTD_p_jobSize:
-        if (cctx->nbThreads <= 1) return ERROR(compressionParameter_unsupported);
+        if (cctx->nbThreads <= 1) return ERROR(parameter_unsupported);
         assert(cctx->mtctx != NULL);
         return ZSTDMT_setMTCtxParameter(cctx->mtctx, ZSTDMT_p_sectionSize, value);
 
     case ZSTD_p_overlapSizeLog:
         DEBUGLOG(5, " setting overlap with nbThreads == %u", cctx->nbThreads);
-        if (cctx->nbThreads <= 1) return ERROR(compressionParameter_unsupported);
+        if (cctx->nbThreads <= 1) return ERROR(parameter_unsupported);
         assert(cctx->mtctx != NULL);
         return ZSTDMT_setMTCtxParameter(cctx->mtctx, ZSTDMT_p_overlapSectionLog, value);
 
-    default: return ERROR(parameter_unknown);
+    default: return ERROR(parameter_unsupported);
     }
 }
 
@@ -451,7 +451,8 @@ size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams)
     CLAMPCHECK(cParams.searchLog, ZSTD_SEARCHLOG_MIN, ZSTD_SEARCHLOG_MAX);
     CLAMPCHECK(cParams.searchLength, ZSTD_SEARCHLENGTH_MIN, ZSTD_SEARCHLENGTH_MAX);
     CLAMPCHECK(cParams.targetLength, ZSTD_TARGETLENGTH_MIN, ZSTD_TARGETLENGTH_MAX);
-    if ((U32)(cParams.strategy) > (U32)ZSTD_btultra) return ERROR(compressionParameter_unsupported);
+    if ((U32)(cParams.strategy) > (U32)ZSTD_btultra)
+        return ERROR(parameter_unsupported);
     return 0;
 }
 
diff --git a/lib/compress/zstdmt_compress.c b/lib/compress/zstdmt_compress.c
index 3be850c6d..ccc20c78a 100644
--- a/lib/compress/zstdmt_compress.c
+++ b/lib/compress/zstdmt_compress.c
@@ -496,7 +496,7 @@ size_t ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSDTMT_parameter parameter,
         mtctx->overlapLog = (value >= 9) ? 9 : value;
         return 0;
     default :
-        return ERROR(compressionParameter_unsupported);
+        return ERROR(parameter_unsupported);
     }
 }
 
diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 4e96504ef..92e80c1ac 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -2227,7 +2227,7 @@ size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds,
 {
     switch(paramType)
     {
-        default : return ERROR(parameter_unknown);
+        default : return ERROR(parameter_unsupported);
         case DStream_p_maxWindowSize : zds->maxWindowSize = paramValue ? paramValue : (U32)(-1); break;
     }
     return 0;
diff --git a/lib/dictBuilder/zdict.c b/lib/dictBuilder/zdict.c
index 742586eac..113d205fc 100644
--- a/lib/dictBuilder/zdict.c
+++ b/lib/dictBuilder/zdict.c
@@ -695,7 +695,7 @@ static size_t ZDICT_analyzeEntropy(void*  dstBuffer, size_t maxDstSize,
         DISPLAYLEVEL(1, "Not enough memory \n");
         goto _cleanup;
     }
-    if (offcodeMax>OFFCODE_MAX) { eSize = ERROR(dictionary_wrong); goto _cleanup; }   /* too large dictionary */
+    if (offcodeMax>OFFCODE_MAX) { eSize = ERROR(dictionaryCreation_failed); goto _cleanup; }   /* too large dictionary */
     for (u=0; u<256; u++) countLit[u] = 1;   /* any character must be described */
     for (u=0; u<=offcodeMax; u++) offcodeCount[u] = 1;
     for (u=0; u<=MaxML; u++) matchLengthCount[u] = 1;
diff --git a/lib/legacy/zstd_v04.c b/lib/legacy/zstd_v04.c
index 8b8e23cb0..2ba75a875 100644
--- a/lib/legacy/zstd_v04.c
+++ b/lib/legacy/zstd_v04.c
@@ -2776,7 +2776,7 @@ static size_t ZSTD_decodeFrameHeader_Part2(ZSTD_DCtx* zc, const void* src, size_
     size_t result;
     if (srcSize != zc->headerSize) return ERROR(srcSize_wrong);
     result = ZSTD_getFrameParams(&(zc->params), src, srcSize);
-    if ((MEM_32bits()) && (zc->params.windowLog > 25)) return ERROR(frameParameter_unsupportedBy32bits);
+    if ((MEM_32bits()) && (zc->params.windowLog > 25)) return ERROR(frameParameter_unsupported);
     return result;
 }
 
diff --git a/lib/legacy/zstd_v05.c b/lib/legacy/zstd_v05.c
index e929618a3..bd3e8c113 100644
--- a/lib/legacy/zstd_v05.c
+++ b/lib/legacy/zstd_v05.c
@@ -2888,7 +2888,7 @@ static size_t ZSTDv05_decodeFrameHeader_Part2(ZSTDv05_DCtx* zc, const void* src,
     if (srcSize != zc->headerSize)
         return ERROR(srcSize_wrong);
     result = ZSTDv05_getFrameParams(&(zc->params), src, srcSize);
-    if ((MEM_32bits()) && (zc->params.windowLog > 25)) return ERROR(frameParameter_unsupportedBy32bits);
+    if ((MEM_32bits()) && (zc->params.windowLog > 25)) return ERROR(frameParameter_unsupported);
     return result;
 }
 
diff --git a/lib/legacy/zstd_v06.c b/lib/legacy/zstd_v06.c
index 26f0929da..3fb47c2bf 100644
--- a/lib/legacy/zstd_v06.c
+++ b/lib/legacy/zstd_v06.c
@@ -3084,7 +3084,7 @@ size_t ZSTDv06_getFrameParams(ZSTDv06_frameParams* fparamsPtr, const void* src,
 static size_t ZSTDv06_decodeFrameHeader(ZSTDv06_DCtx* zc, const void* src, size_t srcSize)
 {
     size_t const result = ZSTDv06_getFrameParams(&(zc->fParams), src, srcSize);
-    if ((MEM_32bits()) && (zc->fParams.windowLog > 25)) return ERROR(frameParameter_unsupportedBy32bits);
+    if ((MEM_32bits()) && (zc->fParams.windowLog > 25)) return ERROR(frameParameter_unsupported);
     return result;
 }