diff --git a/libs/codec/gsm/inc/private.h b/libs/codec/gsm/inc/private.h
index 46071a662d..82efc929ac 100644
--- a/libs/codec/gsm/inc/private.h
+++ b/libs/codec/gsm/inc/private.h
@@ -33,7 +33,7 @@ struct gsm_state {
 	word		v[9];		/* short_term.c, synthesis	*/
 	word		msr;		/* decoder.c,	Postprocessing	*/
 
-	char		verbose;	/* only used if !NDEBUG		*/
+	int			verbose;	/* only used if !NDEBUG		*/
 	char		fast;		/* only used if FAST		*/
 
 	char		wav_fmt;	/* only used if WAV49 defined	*/
diff --git a/libs/codec/gsm/libgsm.vcproj b/libs/codec/gsm/libgsm.vcproj
index 1d36add58c..75e3e4398f 100644
--- a/libs/codec/gsm/libgsm.vcproj
+++ b/libs/codec/gsm/libgsm.vcproj
@@ -46,9 +46,10 @@
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="3"
 				UsePrecompiledHeader="0"
-				WarningLevel="3"
+				WarningLevel="4"
 				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
+				DisableSpecificWarnings="4131;4100"
 			/>
 			<Tool
 				Name="VCManagedResourceCompilerTool"
@@ -107,9 +108,10 @@
 				PreprocessorDefinitions="WIN32;NDEBUG;_LIB"
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
-				WarningLevel="3"
+				WarningLevel="4"
 				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
+				DisableSpecificWarnings="4131;4100"
 			/>
 			<Tool
 				Name="VCManagedResourceCompilerTool"
diff --git a/libs/codec/gsm/src/long_term.c b/libs/codec/gsm/src/long_term.c
index aabd14a42f..954e2060be 100644
--- a/libs/codec/gsm/src/long_term.c
+++ b/libs/codec/gsm/src/long_term.c
@@ -194,7 +194,7 @@ static void Calculation_of_the_LTP_parameters P4((d,dp,bc_out,Nc_out),
 	/*  Initialization of a working array wt
 	 */
 
-	for (k = 0; k <= 39; k++) wt[k] = SASR( d[k], scal );
+	for (k = 0; k <= 39; k++) wt[k] = (word)SASR( d[k], scal );
 
 	/* Search for the maximum cross-correlation and coding of the LTP lag
 	 */
@@ -231,7 +231,7 @@ static void Calculation_of_the_LTP_parameters P4((d,dp,bc_out,Nc_out),
 
 		if (L_result > L_max) {
 
-			Nc    = lambda;
+			Nc    = (word)lambda;
 			L_max = L_result;
 		}
 	}
diff --git a/libs/codec/gsm/src/preprocess.c b/libs/codec/gsm/src/preprocess.c
index b1a7089f67..80981b0078 100644
--- a/libs/codec/gsm/src/preprocess.c
+++ b/libs/codec/gsm/src/preprocess.c
@@ -40,7 +40,7 @@ void Gsm_Preprocess P3((S, s, so),
 
 	word       z1 = S->z1;
 	longword L_z2 = S->L_z2;
-	word 	   mp = S->mp;
+	word 	   mp = (word)S->mp;
 
 	word 	   	s1;
 	longword      L_s2;
@@ -59,7 +59,7 @@ void Gsm_Preprocess P3((S, s, so),
 
 	/*  4.2.1   Downscaling of the input signal
 	 */
-		SO = SASR( *s, 3 ) << 2;
+		SO = (word)SASR( *s, 3 ) << 2;
 		s++;
 
 		assert (SO >= -0x4000);	/* downscaled by     */
diff --git a/libs/codec/gsm/src/rpe.c b/libs/codec/gsm/src/rpe.c
index c6cb05146f..51ab12634d 100644
--- a/libs/codec/gsm/src/rpe.c
+++ b/libs/codec/gsm/src/rpe.c
@@ -232,7 +232,7 @@ static void APCM_quantization_xmaxc_to_exp_mant P3((xmaxc,exp_out,mant_out),
 	 */
 
 	exp = 0;
-	if (xmaxc > 15) exp = SASR(xmaxc, 3) - 1;
+	if (xmaxc > 15) exp = (word)SASR(xmaxc, 3) - 1;
 	mant = xmaxc - (exp << 3);
 
 	if (mant == 0) {
@@ -283,13 +283,13 @@ static void APCM_quantization P5((xM,xMc,mant_out,exp_out,xmaxc_out),
 	 */
 
 	exp   = 0;
-	temp  = SASR( xmax, 9 );
+	temp  = (word)SASR( xmax, 9 );
 	itest = 0;
 
 	for (i = 0; i <= 5; i++) {
 
 		itest |= (temp <= 0);
-		temp = SASR( temp, 1 );
+		temp = (word)SASR( temp, 1 );
 
 		assert(exp <= 5);
 		if (itest == 0) exp++;		/* exp = add (exp, 1) */
@@ -333,7 +333,7 @@ static void APCM_quantization P5((xM,xMc,mant_out,exp_out,xmaxc_out),
 
 		temp = xM[i] << temp1;
 		temp = (word) GSM_MULT( temp, temp2 );
-		temp = SASR(temp, 12);
+		temp = (word)SASR(temp, 12);
 		xMc[i] = temp + 4;		/* see note below */
 	}
 
diff --git a/libs/codec/gsm/src/short_term.c b/libs/codec/gsm/src/short_term.c
index b953d5b262..aeec285899 100644
--- a/libs/codec/gsm/src/short_term.c
+++ b/libs/codec/gsm/src/short_term.c
@@ -167,9 +167,9 @@ static void LARp_to_rp P1((LARp),
 
 		if (*LARp < 0) {
 			temp = *LARp == MIN_WORD ? MAX_WORD : -(*LARp);
-			*LARp = - ((temp < 11059) ? temp << 1
-				: ((temp < 20070) ? temp + 11059
-				:  (word) GSM_ADD( temp >> 2, 26112 )));
+			*LARp =(word)( - ((temp < 11059) ? (word)(temp << 1)
+				: ((temp < 20070) ? (word)(temp + 11059)
+				:  (word) GSM_ADD( temp >> 2, 26112 ))));
 		} else {
 			temp  = *LARp;
 			*LARp =    (temp < 11059) ? temp << 1